Always set added and removed to true or false, rather than le…

…aving them unset or explicitly using `undefined` (kpdecker#455)

* Always set `added` and `removed` to `true` or `false`, rather than leaving them unset or explicitly using `undefined`

Resolves kpdecker#233

* Add release notes

README.md

@@ -145,10 +145,8 @@ All methods above which accept the optional `callback` method will run in sync m
 Many of the methods above return change objects. These objects consist of the following fields:
 
 * `value`: Text content
-* `added`: True if the value was inserted into the new string
-* `removed`: True if the value was removed from the old string
-
-Note that some cases may omit a particular flag field. Comparison on the flag fields should always be done in a truthy or falsy manner.
+* `added`: true if the value was inserted into the new string, otherwise false
+* `removed`: true if the value was removed from the old string, otherwise false
 
 ## Examples
 

release-notes.md

@@ -6,6 +6,7 @@
 
 - [#435](https://github.com/kpdecker/jsdiff/pull/435) Fix `parsePatch` handling of control characters. `parsePatch` used to interpret various unusual control characters - namely vertical tabs, form feeds, lone carriage returns without a line feed, and EBCDIC NELs - as line breaks when parsing a patch file. This was inconsistent with the behavior of both JsDiff's own `diffLines` method and also the Unix `diff` and `patch` utils, which all simply treat those control characters as ordinary characters. The result of this discrepancy was that some well-formed patches - produced either by `diff` or by JsDiff itself and handled properly by the `patch` util - would be wrongly parsed by `parsePatch`, with the effect that it would disregard the remainder of a hunk after encountering one of these control characters.
 - [#439](https://github.com/kpdecker/jsdiff/pull/439) Prefer diffs that order deletions before insertions. When faced with a choice between two diffs with an equal total edit distance, the Myers diff algorithm generally prefers one that does deletions before insertions rather than insertions before deletions. For instance, when diffing `abcd` against `acbd`, it will prefer a diff that says to delete the `b` and then insert a new `b` after the `c`, over a diff that says to insert a `c` before the `b` and then delete the existing `c`. JsDiff deviated from the published Myers algorithm in a way that led to it having the opposite preference in many cases, including that example. This is now fixed, meaning diffs output by JsDiff will more accurately reflect what the published Myers diff algorithm would output.
+- [#455](https://github.com/kpdecker/jsdiff/pull/455) The `added` and `removed` properties of change objects are now guaranteed to be set to a boolean value. (Previously, they would be set to `undefined` or omitted entirely instead of setting them to false.)
 
 ## Development
 

src/diff/base.js

@@ -40,7 +40,7 @@ Diff.prototype = {
     let newPos = this.extractCommon(bestPath[0], newString, oldString, 0);
     if (bestPath[0].oldPos + 1 >= oldLen && newPos + 1 >= newLen) {
       // Identity per the equality and tokenizer
-      return done([{value: this.join(newString), count: newString.length}]);
+      return done([{value: this.join(newString), count: newString.length, added: false, removed: false}]);
     }
 
     // Once we hit the right edge of the edit graph on some diagonal k, we can
@@ -95,9 +95,9 @@ Diff.prototype = {
         // path whose position in the old string is the farthest from the origin
         // and does not pass the bounds of the diff graph
         if (!canRemove || (canAdd && removePath.oldPos < addPath.oldPos)) {
-          basePath = self.addToPath(addPath, true, undefined, 0);
+          basePath = self.addToPath(addPath, true, false, 0);
         } else {
-          basePath = self.addToPath(removePath, undefined, true, 1);
+          basePath = self.addToPath(removePath, false, true, 1);
         }
 
         newPos = self.extractCommon(basePath, newString, oldString, diagonalPath);
@@ -173,7 +173,7 @@ Diff.prototype = {
     }
 
     if (commonCount) {
-      basePath.lastComponent = {count: commonCount, previousComponent: basePath.lastComponent};
+      basePath.lastComponent = {count: commonCount, previousComponent: basePath.lastComponent, added: false, removed: false};
     }
 
     basePath.oldPos = oldPos;

test/diff/array.js

@@ -9,10 +9,10 @@ describe('diff/array', function() {
       const diffResult = diffArrays([a, b, c], [a, c, b]);
       console.log(diffResult);
       expect(diffResult).to.deep.equals([
-          {count: 1, value: [a]},
-          {count: 1, value: [b], removed: true, added: undefined},
-          {count: 1, value: [c]},
-          {count: 1, value: [b], removed: undefined, added: true}
+          {count: 1, value: [a], removed: false, added: false},
+          {count: 1, value: [b], removed: true, added: false},
+          {count: 1, value: [c], removed: false, added: false},
+          {count: 1, value: [b], removed: false, added: true}
       ]);
     });
     it('should diff falsey values', function() {
@@ -24,20 +24,20 @@ describe('diff/array', function() {
       const arrayB = [c, b, a, b, a, c];
       const diffResult = diffArrays(arrayA, arrayB);
       expect(diffResult).to.deep.equals([
-        {count: 2, value: [a, b], removed: true, added: undefined},
-        {count: 1, value: [c]},
-        {count: 1, value: [b], removed: undefined, added: true},
-        {count: 2, value: [a, b]},
-        {count: 1, value: [b], removed: true, added: undefined},
-        {count: 1, value: [a]},
-        {count: 1, value: [c], removed: undefined, added: true}
+        {count: 2, value: [a, b], removed: true, added: false},
+        {count: 1, value: [c], removed: false, added: false},
+        {count: 1, value: [b], removed: false, added: true},
+        {count: 2, value: [a, b], removed: false, added: false},
+        {count: 1, value: [b], removed: true, added: false},
+        {count: 1, value: [a], removed: false, added: false},
+        {count: 1, value: [c], removed: false, added: true}
       ]);
     });
     describe('anti-aliasing', function() {
       // Test apparent contract that no chunk value is ever an input argument.
       const value = [0, 1, 2];
       const expected = [
-        {count: value.length, value: value}
+        {count: value.length, value: value, removed: false, added: false}
       ];
 
       const input = value.slice();
@@ -70,9 +70,9 @@ describe('diff/array', function() {
       const diffResult = diffArrays([a, b, c], [a, b, d], { comparator: comparator });
       console.log(diffResult);
       expect(diffResult).to.deep.equals([
-          {count: 2, value: [a, b]},
-          {count: 1, value: [c], removed: true, added: undefined},
-          {count: 1, value: [d], removed: undefined, added: true}
+          {count: 2, value: [a, b], removed: false, added: false},
+          {count: 1, value: [c], removed: true, added: false},
+          {count: 1, value: [d], removed: false, added: true}
       ]);
     });
   });

test/diff/json.js

@@ -10,9 +10,9 @@ describe('diff/json', function() {
         {a: 123, b: 456, c: 789},
         {a: 123, b: 456}
       )).to.eql([
-        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n' },
-        { count: 1, value: '  "c": 789\n', added: undefined, removed: true },
-        { count: 1, value: '}' }
+        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n', removed: false, added: false },
+        { count: 1, value: '  "c": 789\n', added: false, removed: true },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
     });
 
@@ -21,9 +21,9 @@ describe('diff/json', function() {
         {a: 123, b: 456, c: 789},
         {b: 456, a: 123}
       )).to.eql([
-        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n' },
-        { count: 1, value: '  "c": 789\n', added: undefined, removed: true },
-        { count: 1, value: '}' }
+        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n', removed: false, added: false },
+        { count: 1, value: '  "c": 789\n', added: false, removed: true },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
     });
 
@@ -32,9 +32,9 @@ describe('diff/json', function() {
         {a: 123, b: 456, c: [1, 2, {foo: 'bar'}, 4]},
         {a: 123, b: 456, c: [1, {foo: 'bar'}, 4]}
       )).to.eql([
-        { count: 5, value: '{\n  "a": 123,\n  "b": 456,\n  "c": [\n    1,\n' },
-        { count: 1, value: '    2,\n', added: undefined, removed: true },
-        { count: 6, value: '    {\n      "foo": "bar"\n    },\n    4\n  ]\n}' }
+        { count: 5, value: '{\n  "a": 123,\n  "b": 456,\n  "c": [\n    1,\n', removed: false, added: false },
+        { count: 1, value: '    2,\n', added: false, removed: true },
+        { count: 6, value: '    {\n      "foo": "bar"\n    },\n    4\n  ]\n}', removed: false, added: false }
       ]);
     });
 
@@ -43,12 +43,12 @@ describe('diff/json', function() {
         {a: new Date(123), b: new Date(456), c: new Date(789)},
         {a: new Date(124), b: new Date(456)}
       )).to.eql([
-        { count: 1, value: '{\n' },
-        { count: 1, value: '  "a": "1970-01-01T00:00:00.123Z",\n', added: undefined, removed: true },
-        { count: 1, value: '  "a": "1970-01-01T00:00:00.124Z",\n', added: true, removed: undefined },
-        { count: 1, value: '  "b": "1970-01-01T00:00:00.456Z",\n' },
-        { count: 1, value: '  "c": "1970-01-01T00:00:00.789Z"\n', added: undefined, removed: true },
-        { count: 1, value: '}' }
+        { count: 1, value: '{\n', removed: false, added: false },
+        { count: 1, value: '  "a": "1970-01-01T00:00:00.123Z",\n', added: false, removed: true },
+        { count: 1, value: '  "a": "1970-01-01T00:00:00.124Z",\n', added: true, removed: false },
+        { count: 1, value: '  "b": "1970-01-01T00:00:00.456Z",\n', removed: false, added: false },
+        { count: 1, value: '  "c": "1970-01-01T00:00:00.789Z"\n', added: false, removed: true },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
     });
 
@@ -57,24 +57,24 @@ describe('diff/json', function() {
         {a: 123, b: 456, c: null},
         {a: 123, b: 456}
       )).to.eql([
-        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n' },
-        { count: 1, value: '  "c": null\n', added: undefined, removed: true },
-        { count: 1, value: '}' }
+        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n', removed: false, added: false },
+        { count: 1, value: '  "c": null\n', added: false, removed: true },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
       expect(diffJson(
         {a: 123, b: 456, c: undefined},
         {a: 123, b: 456}
       )).to.eql([
-        { count: 4, value: '{\n  "a": 123,\n  "b": 456\n}' }
+        { count: 4, value: '{\n  "a": 123,\n  "b": 456\n}', removed: false, added: false }
       ]);
       expect(diffJson(
         {a: 123, b: 456, c: undefined},
         {a: 123, b: 456},
         {undefinedReplacement: null}
       )).to.eql([
-        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n' },
-        { count: 1, value: '  "c": null\n', added: undefined, removed: true },
-        { count: 1, value: '}' }
+        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n', removed: false, added: false },
+        { count: 1, value: '  "c": null\n', added: false, removed: true },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
     });
 
@@ -83,9 +83,9 @@ describe('diff/json', function() {
         JSON.stringify({a: 123, b: 456, c: 789}, undefined, '  '),
         JSON.stringify({a: 123, b: 456}, undefined, '  ')
       )).to.eql([
-        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n' },
-        { count: 1, value: '  "c": 789\n', added: undefined, removed: true },
-        { count: 1, value: '}' }
+        { count: 3, value: '{\n  "a": 123,\n  "b": 456,\n', removed: false, added: false },
+        { count: 1, value: '  "c": 789\n', added: false, removed: true },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
     });
 
@@ -143,43 +143,43 @@ describe('diff/json', function() {
         {a: 123},
         {a: /foo/}
       )).to.eql([
-        { count: 1, value: '{\n' },
-        { count: 1, value: '  \"a\": 123\n', added: undefined, removed: true },
-        { count: 1, value: '  \"a\": {}\n', added: true, removed: undefined },
-        { count: 1, value: '}' }
+        { count: 1, value: '{\n', removed: false, added: false },
+        { count: 1, value: '  \"a\": 123\n', added: false, removed: true },
+        { count: 1, value: '  \"a\": {}\n', added: true, removed: false },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
 
       expect(diffJson(
         {a: 123},
         {a: /foo/gi},
         {stringifyReplacer: (k, v) => v instanceof RegExp ? v.toString() : v}
       )).to.eql([
-        { count: 1, value: '{\n' },
-        { count: 1, value: '  \"a\": 123\n', added: undefined, removed: true },
-        { count: 1, value: '  \"a\": "/foo/gi"\n', added: true, removed: undefined },
-        { count: 1, value: '}' }
+        { count: 1, value: '{\n', removed: false, added: false },
+        { count: 1, value: '  \"a\": 123\n', added: false, removed: true },
+        { count: 1, value: '  \"a\": "/foo/gi"\n', added: true, removed: false },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
 
       expect(diffJson(
         {a: 123},
         {a: new Error('ohaider')},
         {stringifyReplacer: (k, v) => v instanceof Error ? `${v.name}: ${v.message}` : v}
       )).to.eql([
-        { count: 1, value: '{\n' },
-        { count: 1, value: '  \"a\": 123\n', added: undefined, removed: true },
-        { count: 1, value: '  \"a\": "Error: ohaider"\n', added: true, removed: undefined },
-        { count: 1, value: '}' }
+        { count: 1, value: '{\n', removed: false, added: false },
+        { count: 1, value: '  \"a\": 123\n', added: false, removed: true },
+        { count: 1, value: '  \"a\": "Error: ohaider"\n', added: true, removed: false },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
 
       expect(diffJson(
         {a: 123},
         {a: [new Error('ohaider')]},
         {stringifyReplacer: (k, v) => v instanceof Error ? `${v.name}: ${v.message}` : v}
       )).to.eql([
-        { count: 1, value: '{\n' },
-        { count: 1, value: '  \"a\": 123\n', added: undefined, removed: true },
-        { count: 3, value: '  \"a\": [\n    "Error: ohaider"\n  ]\n', added: true, removed: undefined },
-        { count: 1, value: '}' }
+        { count: 1, value: '{\n', removed: false, added: false },
+        { count: 1, value: '  \"a\": 123\n', added: false, removed: true },
+        { count: 3, value: '  \"a\": [\n    "Error: ohaider"\n  ]\n', added: true, removed: false },
+        { count: 1, value: '}', removed: false, added: false }
       ]);
     });
   });

test/diff/line.js

@@ -113,18 +113,18 @@ describe('diff/line', function() {
 
   describe('#diffLinesNL', function() {
     expect(diffLines('restaurant', 'restaurant\n', {newlineIsToken: true})).to.eql([
-      {value: 'restaurant', count: 1},
-      {value: '\n', count: 1, added: true, removed: undefined}
+      {value: 'restaurant', count: 1, added: false, removed: false},
+      {value: '\n', count: 1, added: true, removed: false}
     ]);
     expect(diffLines('restaurant', 'restaurant\nhello', {newlineIsToken: true})).to.eql([
-      {value: 'restaurant', count: 1},
-      {value: '\nhello', count: 2, added: true, removed: undefined}
+      {value: 'restaurant', count: 1, added: false, removed: false},
+      {value: '\nhello', count: 2, added: true, removed: false}
     ]);
   });
 
   describe('Strip trailing CR', function() {
     expect(diffLines('line\nline', 'line\r\nline', {stripTrailingCr: true})).to.eql([
-      {value: 'line\nline', count: 2}
+      {value: 'line\nline', count: 2, added: false, removed: false}
     ]);
   });
 });

test/diff/word.js

@@ -67,23 +67,23 @@ describe('WordDiff', function() {
     });
 
     it('should include count with identity cases', function() {
-      expect(diffWords('foo', 'foo')).to.eql([{value: 'foo', count: 1}]);
-      expect(diffWords('foo bar', 'foo bar')).to.eql([{value: 'foo bar', count: 3}]);
+      expect(diffWords('foo', 'foo')).to.eql([{value: 'foo', count: 1, removed: false, added: false}]);
+      expect(diffWords('foo bar', 'foo bar')).to.eql([{value: 'foo bar', count: 3, removed: false, added: false}]);
     });
     it('should include count with empty cases', function() {
-      expect(diffWords('foo', '')).to.eql([{value: 'foo', count: 1, added: undefined, removed: true}]);
-      expect(diffWords('foo bar', '')).to.eql([{value: 'foo bar', count: 3, added: undefined, removed: true}]);
+      expect(diffWords('foo', '')).to.eql([{value: 'foo', count: 1, added: false, removed: true}]);
+      expect(diffWords('foo bar', '')).to.eql([{value: 'foo bar', count: 3, added: false, removed: true}]);
 
-      expect(diffWords('', 'foo')).to.eql([{value: 'foo', count: 1, added: true, removed: undefined}]);
-      expect(diffWords('', 'foo bar')).to.eql([{value: 'foo bar', count: 3, added: true, removed: undefined}]);
+      expect(diffWords('', 'foo')).to.eql([{value: 'foo', count: 1, added: true, removed: false}]);
+      expect(diffWords('', 'foo bar')).to.eql([{value: 'foo bar', count: 3, added: true, removed: false}]);
     });
 
     it('should ignore whitespace', function() {
-      expect(diffWords('hase igel fuchs', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs' }]);
-      expect(diffWords('hase igel fuchs', 'hase igel fuchs\n')).to.eql([{ count: 5, value: 'hase igel fuchs\n' }]);
-      expect(diffWords('hase igel fuchs\n', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs\n' }]);
-      expect(diffWords('hase igel fuchs', 'hase igel\nfuchs')).to.eql([{ count: 5, value: 'hase igel\nfuchs' }]);
-      expect(diffWords('hase igel\nfuchs', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs' }]);
+      expect(diffWords('hase igel fuchs', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs', removed: false, added: false }]);
+      expect(diffWords('hase igel fuchs', 'hase igel fuchs\n')).to.eql([{ count: 5, value: 'hase igel fuchs\n', removed: false, added: false }]);
+      expect(diffWords('hase igel fuchs\n', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs\n', removed: false, added: false }]);
+      expect(diffWords('hase igel fuchs', 'hase igel\nfuchs')).to.eql([{ count: 5, value: 'hase igel\nfuchs', removed: false, added: false }]);
+      expect(diffWords('hase igel\nfuchs', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs', removed: false, added: false }]);
     });
 
     it('should diff whitespace with flag', function() {