diff --git a/lib/jasmine-core/jasmine.js b/lib/jasmine-core/jasmine.js
index 9c86dcda..fa9938e6 100644
--- a/lib/jasmine-core/jasmine.js
+++ b/lib/jasmine-core/jasmine.js
@@ -4926,11 +4926,12 @@ getJasmineRequireObj().toBeResolvedTo = function(j$) {
 
 getJasmineRequireObj().DiffBuilder = function(j$) {
   return function DiffBuilder(config) {
-    var prettyPrinter = (config || {}).prettyPrinter || j$.makePrettyPrinter(),
-      mismatches = new j$.MismatchTree(),
-      path = new j$.ObjectPath(),
-      actualRoot = undefined,
-      expectedRoot = undefined;
+    const prettyPrinter =
+      (config || {}).prettyPrinter || j$.makePrettyPrinter();
+    const mismatches = new j$.MismatchTree();
+    let path = new j$.ObjectPath();
+    let actualRoot = undefined;
+    let expectedRoot = undefined;
 
     return {
       setRoots: function(actual, expected) {
@@ -4943,29 +4944,24 @@ getJasmineRequireObj().DiffBuilder = function(j$) {
       },
 
       getMessage: function() {
-        var messages = [];
+        const messages = [];
 
         mismatches.traverse(function(path, isLeaf, formatter) {
-          var actualCustom,
-            expectedCustom,
-            useCustom,
-            derefResult = dereferencePath(
-              path,
-              actualRoot,
-              expectedRoot,
-              prettyPrinter
-            ),
-            actual = derefResult.actual,
-            expected = derefResult.expected;
+          const { actual, expected } = dereferencePath(
+            path,
+            actualRoot,
+            expectedRoot,
+            prettyPrinter
+          );
 
           if (formatter) {
             messages.push(formatter(actual, expected, path, prettyPrinter));
             return true;
           }
 
-          actualCustom = prettyPrinter.customFormat_(actual);
-          expectedCustom = prettyPrinter.customFormat_(expected);
-          useCustom = !(
+          const actualCustom = prettyPrinter.customFormat_(actual);
+          const expectedCustom = prettyPrinter.customFormat_(expected);
+          const useCustom = !(
             j$.util.isUndefined(actualCustom) &&
             j$.util.isUndefined(expectedCustom)
           );
@@ -4990,7 +4986,7 @@ getJasmineRequireObj().DiffBuilder = function(j$) {
       },
 
       withPath: function(pathComponent, block) {
-        var oldPath = path;
+        const oldPath = path;
         path = path.add(pathComponent);
         block();
         path = oldPath;
@@ -5024,18 +5020,17 @@ getJasmineRequireObj().DiffBuilder = function(j$) {
         j$.isAsymmetricEqualityTester_(expected) &&
         j$.isFunction_(expected.valuesForDiff_)
       ) {
-        var asymmetricResult = expected.valuesForDiff_(actual, pp);
+        const asymmetricResult = expected.valuesForDiff_(actual, pp);
         expected = asymmetricResult.self;
         actual = asymmetricResult.other;
       }
     }
 
-    var i;
     handleAsymmetricExpected();
 
-    for (i = 0; i < objectPath.components.length; i++) {
-      actual = actual[objectPath.components[i]];
-      expected = expected[objectPath.components[i]];
+    for (const pc of objectPath.components) {
+      actual = actual[pc];
+      expected = expected[pc];
       handleAsymmetricExpected();
     }
 
@@ -5748,15 +5743,13 @@ getJasmineRequireObj().MismatchTree = function(j$) {
   }
 
   MismatchTree.prototype.add = function(path, formatter) {
-    var key, child;
-
     if (path.depth() === 0) {
       this.formatter = formatter;
       this.isMismatch = true;
     } else {
-      key = path.components[0];
+      const key = path.components[0];
       path = path.shift();
-      child = this.child(key);
+      let child = this.child(key);
 
       if (!child) {
         child = new MismatchTree(this.path.add(key));
@@ -5768,27 +5761,22 @@ getJasmineRequireObj().MismatchTree = function(j$) {
   };
 
   MismatchTree.prototype.traverse = function(visit) {
-    var i,
-      hasChildren = this.children.length > 0;
+    const hasChildren = this.children.length > 0;
 
     if (this.isMismatch || hasChildren) {
       if (visit(this.path, !hasChildren, this.formatter)) {
-        for (i = 0; i < this.children.length; i++) {
-          this.children[i].traverse(visit);
+        for (const child of this.children) {
+          child.traverse(visit);
         }
       }
     }
   };
 
   MismatchTree.prototype.child = function(key) {
-    var i, pathEls;
-
-    for (i = 0; i < this.children.length; i++) {
-      pathEls = this.children[i].path.components;
-      if (pathEls[pathEls.length - 1] === key) {
-        return this.children[i];
-      }
-    }
+    return this.children.find(child => {
+      const pathEls = child.path.components;
+      return pathEls[pathEls.length - 1] === key;
+    });
   };
 
   return MismatchTree;
@@ -5835,7 +5823,7 @@ getJasmineRequireObj().ObjectPath = function(j$) {
 
   ObjectPath.prototype.toString = function() {
     if (this.components.length) {
-      return '$' + map(this.components, formatPropertyAccess).join('');
+      return '$' + this.components.map(formatPropertyAccess).join('');
     } else {
       return '';
     }
@@ -5865,14 +5853,6 @@ getJasmineRequireObj().ObjectPath = function(j$) {
     return "['" + prop + "']";
   }
 
-  function map(array, fn) {
-    var results = [];
-    for (var i = 0; i < array.length; i++) {
-      results.push(fn(array[i]));
-    }
-    return results;
-  }
-
   function isValidIdentifier(string) {
     return /^[A-Za-z\$_][A-Za-z0-9\$_]*$/.test(string);
   }
@@ -7568,7 +7548,7 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   SinglePrettyPrintRun.prototype.format = function(value) {
     this.ppNestLevel_++;
     try {
-      var customFormatResult = this.applyCustomFormatters_(value);
+      const customFormatResult = this.applyCustomFormatters_(value);
 
       if (customFormatResult) {
         this.emitScalar(customFormatResult);
@@ -7648,10 +7628,10 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   };
 
   SinglePrettyPrintRun.prototype.iterateObject = function(obj, fn) {
-    var objKeys = j$.MatchersUtil.keys(obj, j$.isArray_(obj));
-    var length = Math.min(objKeys.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
+    const objKeys = j$.MatchersUtil.keys(obj, j$.isArray_(obj));
+    const length = Math.min(objKeys.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
 
-    for (var i = 0; i < length; i++) {
+    for (let i = 0; i < length; i++) {
       fn(objKeys[i]);
     }
 
@@ -7671,9 +7651,11 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       this.append('Array');
       return;
     }
-    var length = Math.min(array.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
+
+    const length = Math.min(array.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
     this.append('[ ');
-    for (var i = 0; i < length; i++) {
+
+    for (let i = 0; i < length; i++) {
       if (i > 0) {
         this.append(', ');
       }
@@ -7683,19 +7665,18 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       this.append(', ...');
     }
 
-    var self = this;
-    var first = array.length === 0;
-    var truncated = this.iterateObject(array, function(property) {
+    let first = array.length === 0;
+    const wasTruncated = this.iterateObject(array, property => {
       if (first) {
         first = false;
       } else {
-        self.append(', ');
+        this.append(', ');
       }
 
-      self.formatProperty(array, property);
+      this.formatProperty(array, property);
     });
 
-    if (truncated) {
+    if (wasTruncated) {
       this.append(', ...');
     }
 
@@ -7708,8 +7689,8 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       return;
     }
     this.append('Set( ');
-    var size = Math.min(set.size, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
-    var i = 0;
+    const size = Math.min(set.size, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
+    let i = 0;
     set.forEach(function(value, key) {
       if (i >= size) {
         return;
@@ -7733,8 +7714,8 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       return;
     }
     this.append('Map( ');
-    var size = Math.min(map.size, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
-    var i = 0;
+    const size = Math.min(map.size, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
+    let i = 0;
     map.forEach(function(value, key) {
       if (i >= size) {
         return;
@@ -7753,10 +7734,8 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   };
 
   SinglePrettyPrintRun.prototype.emitObject = function(obj) {
-    var ctor = obj.constructor,
-      constructorName;
-
-    constructorName =
+    const ctor = obj.constructor;
+    const constructorName =
       typeof ctor === 'function' && obj instanceof ctor
         ? j$.fnNameFor(obj.constructor)
         : 'null';
@@ -7767,21 +7746,20 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       return;
     }
 
-    var self = this;
     this.append('({ ');
-    var first = true;
+    let first = true;
 
-    var truncated = this.iterateObject(obj, function(property) {
+    const wasTruncated = this.iterateObject(obj, property => {
       if (first) {
         first = false;
       } else {
-        self.append(', ');
+        this.append(', ');
       }
 
-      self.formatProperty(obj, property);
+      this.formatProperty(obj, property);
     });
 
-    if (truncated) {
+    if (wasTruncated) {
       this.append(', ...');
     }
 
@@ -7789,13 +7767,13 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   };
 
   SinglePrettyPrintRun.prototype.emitTypedArray = function(arr) {
-    var constructorName = j$.fnNameFor(arr.constructor),
-      limitedArray = Array.prototype.slice.call(
-        arr,
-        0,
-        j$.MAX_PRETTY_PRINT_ARRAY_LENGTH
-      ),
-      itemsString = Array.prototype.join.call(limitedArray, ', ');
+    const constructorName = j$.fnNameFor(arr.constructor);
+    const limitedArray = Array.prototype.slice.call(
+      arr,
+      0,
+      j$.MAX_PRETTY_PRINT_ARRAY_LENGTH
+    );
+    let itemsString = Array.prototype.join.call(limitedArray, ', ');
 
     if (limitedArray.length !== arr.length) {
       itemsString += ', ...';
@@ -7805,15 +7783,10 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   };
 
   SinglePrettyPrintRun.prototype.emitDomElement = function(el) {
-    var tagName = el.tagName.toLowerCase(),
-      attrs = el.attributes,
-      i,
-      len = attrs.length,
-      out = '<' + tagName,
-      attr;
+    const tagName = el.tagName.toLowerCase();
+    let out = '<' + tagName;
 
-    for (i = 0; i < len; i++) {
-      attr = attrs[i];
+    for (const attr of el.attributes) {
       out += ' ' + attr.name;
 
       if (attr.value !== '') {
@@ -7848,7 +7821,7 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       value = Object.prototype.toString.call(value);
     }
 
-    var result = truncate(value, j$.MAX_PRETTY_PRINT_CHARS - this.length);
+    const result = truncate(value, j$.MAX_PRETTY_PRINT_CHARS - this.length);
     this.length += result.value.length;
     this.stringParts.push(result.value);
 
@@ -7876,10 +7849,8 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   MaxCharsReachedError.prototype = new Error();
 
   function customFormat(value, customObjectFormatters) {
-    var i, result;
-
-    for (i = 0; i < customObjectFormatters.length; i++) {
-      result = customObjectFormatters[i](value);
+    for (const formatter of customObjectFormatters) {
+      const result = formatter(value);
 
       if (result !== undefined) {
         return result;
@@ -7890,8 +7861,11 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   return function(customObjectFormatters) {
     customObjectFormatters = customObjectFormatters || [];
 
-    var pp = function(value) {
-      var prettyPrinter = new SinglePrettyPrintRun(customObjectFormatters, pp);
+    const pp = function(value) {
+      const prettyPrinter = new SinglePrettyPrintRun(
+        customObjectFormatters,
+        pp
+      );
       prettyPrinter.format(value);
       return prettyPrinter.stringParts.join('');
     };
diff --git a/src/core/PrettyPrinter.js b/src/core/PrettyPrinter.js
index 08f3c925..8e1dae36 100644
--- a/src/core/PrettyPrinter.js
+++ b/src/core/PrettyPrinter.js
@@ -26,7 +26,7 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   SinglePrettyPrintRun.prototype.format = function(value) {
     this.ppNestLevel_++;
     try {
-      var customFormatResult = this.applyCustomFormatters_(value);
+      const customFormatResult = this.applyCustomFormatters_(value);
 
       if (customFormatResult) {
         this.emitScalar(customFormatResult);
@@ -106,10 +106,10 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   };
 
   SinglePrettyPrintRun.prototype.iterateObject = function(obj, fn) {
-    var objKeys = j$.MatchersUtil.keys(obj, j$.isArray_(obj));
-    var length = Math.min(objKeys.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
+    const objKeys = j$.MatchersUtil.keys(obj, j$.isArray_(obj));
+    const length = Math.min(objKeys.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
 
-    for (var i = 0; i < length; i++) {
+    for (let i = 0; i < length; i++) {
       fn(objKeys[i]);
     }
 
@@ -129,9 +129,11 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       this.append('Array');
       return;
     }
-    var length = Math.min(array.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
+
+    const length = Math.min(array.length, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
     this.append('[ ');
-    for (var i = 0; i < length; i++) {
+
+    for (let i = 0; i < length; i++) {
       if (i > 0) {
         this.append(', ');
       }
@@ -141,19 +143,18 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       this.append(', ...');
     }
 
-    var self = this;
-    var first = array.length === 0;
-    var truncated = this.iterateObject(array, function(property) {
+    let first = array.length === 0;
+    const wasTruncated = this.iterateObject(array, property => {
       if (first) {
         first = false;
       } else {
-        self.append(', ');
+        this.append(', ');
       }
 
-      self.formatProperty(array, property);
+      this.formatProperty(array, property);
     });
 
-    if (truncated) {
+    if (wasTruncated) {
       this.append(', ...');
     }
 
@@ -166,8 +167,8 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       return;
     }
     this.append('Set( ');
-    var size = Math.min(set.size, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
-    var i = 0;
+    const size = Math.min(set.size, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
+    let i = 0;
     set.forEach(function(value, key) {
       if (i >= size) {
         return;
@@ -191,8 +192,8 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       return;
     }
     this.append('Map( ');
-    var size = Math.min(map.size, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
-    var i = 0;
+    const size = Math.min(map.size, j$.MAX_PRETTY_PRINT_ARRAY_LENGTH);
+    let i = 0;
     map.forEach(function(value, key) {
       if (i >= size) {
         return;
@@ -211,10 +212,8 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   };
 
   SinglePrettyPrintRun.prototype.emitObject = function(obj) {
-    var ctor = obj.constructor,
-      constructorName;
-
-    constructorName =
+    const ctor = obj.constructor;
+    const constructorName =
       typeof ctor === 'function' && obj instanceof ctor
         ? j$.fnNameFor(obj.constructor)
         : 'null';
@@ -225,21 +224,20 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       return;
     }
 
-    var self = this;
     this.append('({ ');
-    var first = true;
+    let first = true;
 
-    var truncated = this.iterateObject(obj, function(property) {
+    const wasTruncated = this.iterateObject(obj, property => {
       if (first) {
         first = false;
       } else {
-        self.append(', ');
+        this.append(', ');
       }
 
-      self.formatProperty(obj, property);
+      this.formatProperty(obj, property);
     });
 
-    if (truncated) {
+    if (wasTruncated) {
       this.append(', ...');
     }
 
@@ -247,13 +245,13 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   };
 
   SinglePrettyPrintRun.prototype.emitTypedArray = function(arr) {
-    var constructorName = j$.fnNameFor(arr.constructor),
-      limitedArray = Array.prototype.slice.call(
-        arr,
-        0,
-        j$.MAX_PRETTY_PRINT_ARRAY_LENGTH
-      ),
-      itemsString = Array.prototype.join.call(limitedArray, ', ');
+    const constructorName = j$.fnNameFor(arr.constructor);
+    const limitedArray = Array.prototype.slice.call(
+      arr,
+      0,
+      j$.MAX_PRETTY_PRINT_ARRAY_LENGTH
+    );
+    let itemsString = Array.prototype.join.call(limitedArray, ', ');
 
     if (limitedArray.length !== arr.length) {
       itemsString += ', ...';
@@ -263,15 +261,10 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   };
 
   SinglePrettyPrintRun.prototype.emitDomElement = function(el) {
-    var tagName = el.tagName.toLowerCase(),
-      attrs = el.attributes,
-      i,
-      len = attrs.length,
-      out = '<' + tagName,
-      attr;
+    const tagName = el.tagName.toLowerCase();
+    let out = '<' + tagName;
 
-    for (i = 0; i < len; i++) {
-      attr = attrs[i];
+    for (const attr of el.attributes) {
       out += ' ' + attr.name;
 
       if (attr.value !== '') {
@@ -306,7 +299,7 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
       value = Object.prototype.toString.call(value);
     }
 
-    var result = truncate(value, j$.MAX_PRETTY_PRINT_CHARS - this.length);
+    const result = truncate(value, j$.MAX_PRETTY_PRINT_CHARS - this.length);
     this.length += result.value.length;
     this.stringParts.push(result.value);
 
@@ -334,10 +327,8 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   MaxCharsReachedError.prototype = new Error();
 
   function customFormat(value, customObjectFormatters) {
-    var i, result;
-
-    for (i = 0; i < customObjectFormatters.length; i++) {
-      result = customObjectFormatters[i](value);
+    for (const formatter of customObjectFormatters) {
+      const result = formatter(value);
 
       if (result !== undefined) {
         return result;
@@ -348,8 +339,11 @@ getJasmineRequireObj().makePrettyPrinter = function(j$) {
   return function(customObjectFormatters) {
     customObjectFormatters = customObjectFormatters || [];
 
-    var pp = function(value) {
-      var prettyPrinter = new SinglePrettyPrintRun(customObjectFormatters, pp);
+    const pp = function(value) {
+      const prettyPrinter = new SinglePrettyPrintRun(
+        customObjectFormatters,
+        pp
+      );
       prettyPrinter.format(value);
       return prettyPrinter.stringParts.join('');
     };
diff --git a/src/core/matchers/DiffBuilder.js b/src/core/matchers/DiffBuilder.js
index c8c0e497..50da9a69 100644
--- a/src/core/matchers/DiffBuilder.js
+++ b/src/core/matchers/DiffBuilder.js
@@ -1,10 +1,11 @@
 getJasmineRequireObj().DiffBuilder = function(j$) {
   return function DiffBuilder(config) {
-    var prettyPrinter = (config || {}).prettyPrinter || j$.makePrettyPrinter(),
-      mismatches = new j$.MismatchTree(),
-      path = new j$.ObjectPath(),
-      actualRoot = undefined,
-      expectedRoot = undefined;
+    const prettyPrinter =
+      (config || {}).prettyPrinter || j$.makePrettyPrinter();
+    const mismatches = new j$.MismatchTree();
+    let path = new j$.ObjectPath();
+    let actualRoot = undefined;
+    let expectedRoot = undefined;
 
     return {
       setRoots: function(actual, expected) {
@@ -17,29 +18,24 @@ getJasmineRequireObj().DiffBuilder = function(j$) {
       },
 
       getMessage: function() {
-        var messages = [];
+        const messages = [];
 
         mismatches.traverse(function(path, isLeaf, formatter) {
-          var actualCustom,
-            expectedCustom,
-            useCustom,
-            derefResult = dereferencePath(
-              path,
-              actualRoot,
-              expectedRoot,
-              prettyPrinter
-            ),
-            actual = derefResult.actual,
-            expected = derefResult.expected;
+          const { actual, expected } = dereferencePath(
+            path,
+            actualRoot,
+            expectedRoot,
+            prettyPrinter
+          );
 
           if (formatter) {
             messages.push(formatter(actual, expected, path, prettyPrinter));
             return true;
           }
 
-          actualCustom = prettyPrinter.customFormat_(actual);
-          expectedCustom = prettyPrinter.customFormat_(expected);
-          useCustom = !(
+          const actualCustom = prettyPrinter.customFormat_(actual);
+          const expectedCustom = prettyPrinter.customFormat_(expected);
+          const useCustom = !(
             j$.util.isUndefined(actualCustom) &&
             j$.util.isUndefined(expectedCustom)
           );
@@ -64,7 +60,7 @@ getJasmineRequireObj().DiffBuilder = function(j$) {
       },
 
       withPath: function(pathComponent, block) {
-        var oldPath = path;
+        const oldPath = path;
         path = path.add(pathComponent);
         block();
         path = oldPath;
@@ -98,18 +94,17 @@ getJasmineRequireObj().DiffBuilder = function(j$) {
         j$.isAsymmetricEqualityTester_(expected) &&
         j$.isFunction_(expected.valuesForDiff_)
       ) {
-        var asymmetricResult = expected.valuesForDiff_(actual, pp);
+        const asymmetricResult = expected.valuesForDiff_(actual, pp);
         expected = asymmetricResult.self;
         actual = asymmetricResult.other;
       }
     }
 
-    var i;
     handleAsymmetricExpected();
 
-    for (i = 0; i < objectPath.components.length; i++) {
-      actual = actual[objectPath.components[i]];
-      expected = expected[objectPath.components[i]];
+    for (const pc of objectPath.components) {
+      actual = actual[pc];
+      expected = expected[pc];
       handleAsymmetricExpected();
     }
 
diff --git a/src/core/matchers/MismatchTree.js b/src/core/matchers/MismatchTree.js
index 3fdab889..9836b2d9 100644
--- a/src/core/matchers/MismatchTree.js
+++ b/src/core/matchers/MismatchTree.js
@@ -14,15 +14,13 @@ getJasmineRequireObj().MismatchTree = function(j$) {
   }
 
   MismatchTree.prototype.add = function(path, formatter) {
-    var key, child;
-
     if (path.depth() === 0) {
       this.formatter = formatter;
       this.isMismatch = true;
     } else {
-      key = path.components[0];
+      const key = path.components[0];
       path = path.shift();
-      child = this.child(key);
+      let child = this.child(key);
 
       if (!child) {
         child = new MismatchTree(this.path.add(key));
@@ -34,27 +32,22 @@ getJasmineRequireObj().MismatchTree = function(j$) {
   };
 
   MismatchTree.prototype.traverse = function(visit) {
-    var i,
-      hasChildren = this.children.length > 0;
+    const hasChildren = this.children.length > 0;
 
     if (this.isMismatch || hasChildren) {
       if (visit(this.path, !hasChildren, this.formatter)) {
-        for (i = 0; i < this.children.length; i++) {
-          this.children[i].traverse(visit);
+        for (const child of this.children) {
+          child.traverse(visit);
         }
       }
     }
   };
 
   MismatchTree.prototype.child = function(key) {
-    var i, pathEls;
-
-    for (i = 0; i < this.children.length; i++) {
-      pathEls = this.children[i].path.components;
-      if (pathEls[pathEls.length - 1] === key) {
-        return this.children[i];
-      }
-    }
+    return this.children.find(child => {
+      const pathEls = child.path.components;
+      return pathEls[pathEls.length - 1] === key;
+    });
   };
 
   return MismatchTree;
diff --git a/src/core/matchers/ObjectPath.js b/src/core/matchers/ObjectPath.js
index e287af19..f4225d5c 100644
--- a/src/core/matchers/ObjectPath.js
+++ b/src/core/matchers/ObjectPath.js
@@ -5,7 +5,7 @@ getJasmineRequireObj().ObjectPath = function(j$) {
 
   ObjectPath.prototype.toString = function() {
     if (this.components.length) {
-      return '$' + map(this.components, formatPropertyAccess).join('');
+      return '$' + this.components.map(formatPropertyAccess).join('');
     } else {
       return '';
     }
@@ -35,14 +35,6 @@ getJasmineRequireObj().ObjectPath = function(j$) {
     return "['" + prop + "']";
   }
 
-  function map(array, fn) {
-    var results = [];
-    for (var i = 0; i < array.length; i++) {
-      results.push(fn(array[i]));
-    }
-    return results;
-  }
-
   function isValidIdentifier(string) {
     return /^[A-Za-z\$_][A-Za-z0-9\$_]*$/.test(string);
   }