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2.0.0-beta3 (#4594) * Don’t confuse the syntax highlighter * Comment Assign::compilePatternMatch a bit * Assignment expressions in conditionals are a bad practice * Rename `wrapInBraces` to `wrapInParentheses`, to set the stage for future `wrapInBraces` that uses `{` and `wrapInBrackets` that uses `[` * Correct comment * object destructuring * Allow custom position of the rest element. * Output simple array destructuring assignments to ES2015 * Output simple object destructured assignments to ES2015 * Compile shorthand object properties to ES2015 shorthand properties This dramatically improves the appearance of destructured imports. * Don’t confuse the syntax highlighter * Comment Assign::compilePatternMatch a bit * Assignment expressions in conditionals are a bad practice * Rename `wrapInBraces` to `wrapInParentheses`, to set the stage for future `wrapInBraces` that uses `{` and `wrapInBrackets` that uses `[` * object destructuring * Allow custom position of the rest element. * rest element in object destructuring * rest element in object destructuring * fix string interpolation * merging * fixing splats in object literal * Rest element in parameter destructuring * merging with CS2 * merged with CS2 * Add support for the object spread initializer. https://github.com/tc39/proposal-object-rest-spread/blob/master/Spread.md * Fix misspellings, trailing whitespace, other minor details * merging with beta2 * refactor object spread properties * small fix * - Fixed object spread function parameters. - Clean up "Assign" and moved all logic for object rest properties in single method (compileObjectDestruct). - Add helper function "objectWithoutKeys" to the "UTILITIES" for use with object rest properties, e.g. {a, b, r...} = obj => {a, b} = obj, r = objectWithoutKeys(...) - Clean up "Obj" and moved all logic for object spread properties in single method (compileSpread). - Clean up "Code". - Add method "hasSplat" to "Obj" and "Value" for checking if Obj contains the splat. - Enable placing spread syntax triple dots on either right or left, per #85 (https://github.com/coffeescript6/discuss/issues/85) * Fixed typos * Remove unused code * Removed dots (e.g. splat) on the left side from the grammar * Initial release for deep spread properties, e.g. obj2 = {obj.b..., a: 1} or {obj[b][c]..., d: 7} Tests need to be prepared! * 1. Object literal spread properties Object literals: - obj = { {b:{c:{d:1}}}..., a:1 } Parenthetical: - obj = { ( body ), a:1 } - obj = { ( body )..., a:1 } Invocation: - obj = { ( (args) -> ... )(params), a:1 } - obj = { ( (args) -> ... )(params)..., a:1 } - obj = { foo(), a:1 } - obj = { foo()..., a:1 } 2. Refactor, cleanup & other optimizations. * Merged with 2.0 * Cleanup * Some more cleanup. * Fixed error with freeVariable and object destructuring. * Fixed errors with object spread properties. * Improvements, fixed errors. * Minor improvement. * Minor improvements. * Typo. * Remove unnecessary whitespace. * Remove unnecessary whitespace. * Changed few "assertErrorFormat" tests since parentheses are now allowed in the Obj. * Whitespace cleanup * Comments cleanup * fix destructured obj param declarations * refine fix; add test * Refactor function args ({a, b...}) * Additional tests for object destructuring in function argument. * Minor improvement for object destructuring variable declaration. * refactor function args ({a, b...}) and ({a, b...} = {}); Obj And Param cleanup * fix comment * Fix object destructuring variable declaration. * more tests with default values * fix typo * Fixed default values in object destructuring. * small fix * Babel’s tests for object rest spread * Style: spaces after colons in object declarations * Cleanup comments * Simplify Babel tests * Fix comments * Fix destructuring with splats in multiple objects * Add test for default values in detsructuring assignment with splats * Handle default values when assigning to object splats * Rewrite traverseRest to fix handling of dynamic keys * Fix double parens around destructuring with splats * Update compileObjectDestruct comments * Improve formatting of top-level destructures with splats and tidy parens * Added a bigger destructuring-with-defaults test and fixed a bug * Refactor destructuring grammar to allow additional forms * Add a missing case to ObjSpreadExpr * These tests shouldn’t run in the browser * Fix test.html * Fix docs scroll position getting screwed up by CodeMirror initialization * Breaking change documentation about => (fixes #4593) * Spread/rest syntax documentation * Documentation about bound class methods * 2.0.0-beta3 changelog * Add note about ‘lib’ * Fix accidentally converting this to tabs * Bump version to 2.0.0-beta3 * Update annotated source and test.html
2017-06-30 16:58:05 +00:00
## Splats, or Rest Parameters/Spread Syntax
Documentation is now markdown, converted to HTML on compilation
2016-12-08 08:19:55 +00:00
2.0.0-beta3 (#4594) * Don’t confuse the syntax highlighter * Comment Assign::compilePatternMatch a bit * Assignment expressions in conditionals are a bad practice * Rename `wrapInBraces` to `wrapInParentheses`, to set the stage for future `wrapInBraces` that uses `{` and `wrapInBrackets` that uses `[` * Correct comment * object destructuring * Allow custom position of the rest element. * Output simple array destructuring assignments to ES2015 * Output simple object destructured assignments to ES2015 * Compile shorthand object properties to ES2015 shorthand properties This dramatically improves the appearance of destructured imports. * Don’t confuse the syntax highlighter * Comment Assign::compilePatternMatch a bit * Assignment expressions in conditionals are a bad practice * Rename `wrapInBraces` to `wrapInParentheses`, to set the stage for future `wrapInBraces` that uses `{` and `wrapInBrackets` that uses `[` * object destructuring * Allow custom position of the rest element. * rest element in object destructuring * rest element in object destructuring * fix string interpolation * merging * fixing splats in object literal * Rest element in parameter destructuring * merging with CS2 * merged with CS2 * Add support for the object spread initializer. https://github.com/tc39/proposal-object-rest-spread/blob/master/Spread.md * Fix misspellings, trailing whitespace, other minor details * merging with beta2 * refactor object spread properties * small fix * - Fixed object spread function parameters. - Clean up "Assign" and moved all logic for object rest properties in single method (compileObjectDestruct). - Add helper function "objectWithoutKeys" to the "UTILITIES" for use with object rest properties, e.g. {a, b, r...} = obj => {a, b} = obj, r = objectWithoutKeys(...) - Clean up "Obj" and moved all logic for object spread properties in single method (compileSpread). - Clean up "Code". - Add method "hasSplat" to "Obj" and "Value" for checking if Obj contains the splat. - Enable placing spread syntax triple dots on either right or left, per #85 (https://github.com/coffeescript6/discuss/issues/85) * Fixed typos * Remove unused code * Removed dots (e.g. splat) on the left side from the grammar * Initial release for deep spread properties, e.g. obj2 = {obj.b..., a: 1} or {obj[b][c]..., d: 7} Tests need to be prepared! * 1. Object literal spread properties Object literals: - obj = { {b:{c:{d:1}}}..., a:1 } Parenthetical: - obj = { ( body ), a:1 } - obj = { ( body )..., a:1 } Invocation: - obj = { ( (args) -> ... )(params), a:1 } - obj = { ( (args) -> ... )(params)..., a:1 } - obj = { foo(), a:1 } - obj = { foo()..., a:1 } 2. Refactor, cleanup & other optimizations. * Merged with 2.0 * Cleanup * Some more cleanup. * Fixed error with freeVariable and object destructuring. * Fixed errors with object spread properties. * Improvements, fixed errors. * Minor improvement. * Minor improvements. * Typo. * Remove unnecessary whitespace. * Remove unnecessary whitespace. * Changed few "assertErrorFormat" tests since parentheses are now allowed in the Obj. * Whitespace cleanup * Comments cleanup * fix destructured obj param declarations * refine fix; add test * Refactor function args ({a, b...}) * Additional tests for object destructuring in function argument. * Minor improvement for object destructuring variable declaration. * refactor function args ({a, b...}) and ({a, b...} = {}); Obj And Param cleanup * fix comment * Fix object destructuring variable declaration. * more tests with default values * fix typo * Fixed default values in object destructuring. * small fix * Babel’s tests for object rest spread * Style: spaces after colons in object declarations * Cleanup comments * Simplify Babel tests * Fix comments * Fix destructuring with splats in multiple objects * Add test for default values in detsructuring assignment with splats * Handle default values when assigning to object splats * Rewrite traverseRest to fix handling of dynamic keys * Fix double parens around destructuring with splats * Update compileObjectDestruct comments * Improve formatting of top-level destructures with splats and tidy parens * Added a bigger destructuring-with-defaults test and fixed a bug * Refactor destructuring grammar to allow additional forms * Add a missing case to ObjSpreadExpr * These tests shouldn’t run in the browser * Fix test.html * Fix docs scroll position getting screwed up by CodeMirror initialization * Breaking change documentation about => (fixes #4593) * Spread/rest syntax documentation * Documentation about bound class methods * 2.0.0-beta3 changelog * Add note about ‘lib’ * Fix accidentally converting this to tabs * Bump version to 2.0.0-beta3 * Update annotated source and test.html
2017-06-30 16:58:05 +00:00
The JavaScript `arguments` object is a useful way to work with functions that accept variable numbers of arguments. CoffeeScript provides splats `...`, both for function definition as well as invocation, making variable numbers of arguments a little bit more palatable. ES2015 adopted this feature as their [rest parameters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/rest_parameters).
Documentation is now markdown, converted to HTML on compilation
2016-12-08 08:19:55 +00:00
```
codeFor('splats', true)
```
2.0.0-beta3 (#4594) * Don’t confuse the syntax highlighter * Comment Assign::compilePatternMatch a bit * Assignment expressions in conditionals are a bad practice * Rename `wrapInBraces` to `wrapInParentheses`, to set the stage for future `wrapInBraces` that uses `{` and `wrapInBrackets` that uses `[` * Correct comment * object destructuring * Allow custom position of the rest element. * Output simple array destructuring assignments to ES2015 * Output simple object destructured assignments to ES2015 * Compile shorthand object properties to ES2015 shorthand properties This dramatically improves the appearance of destructured imports. * Don’t confuse the syntax highlighter * Comment Assign::compilePatternMatch a bit * Assignment expressions in conditionals are a bad practice * Rename `wrapInBraces` to `wrapInParentheses`, to set the stage for future `wrapInBraces` that uses `{` and `wrapInBrackets` that uses `[` * object destructuring * Allow custom position of the rest element. * rest element in object destructuring * rest element in object destructuring * fix string interpolation * merging * fixing splats in object literal * Rest element in parameter destructuring * merging with CS2 * merged with CS2 * Add support for the object spread initializer. https://github.com/tc39/proposal-object-rest-spread/blob/master/Spread.md * Fix misspellings, trailing whitespace, other minor details * merging with beta2 * refactor object spread properties * small fix * - Fixed object spread function parameters. - Clean up "Assign" and moved all logic for object rest properties in single method (compileObjectDestruct). - Add helper function "objectWithoutKeys" to the "UTILITIES" for use with object rest properties, e.g. {a, b, r...} = obj => {a, b} = obj, r = objectWithoutKeys(...) - Clean up "Obj" and moved all logic for object spread properties in single method (compileSpread). - Clean up "Code". - Add method "hasSplat" to "Obj" and "Value" for checking if Obj contains the splat. - Enable placing spread syntax triple dots on either right or left, per #85 (https://github.com/coffeescript6/discuss/issues/85) * Fixed typos * Remove unused code * Removed dots (e.g. splat) on the left side from the grammar * Initial release for deep spread properties, e.g. obj2 = {obj.b..., a: 1} or {obj[b][c]..., d: 7} Tests need to be prepared! * 1. Object literal spread properties Object literals: - obj = { {b:{c:{d:1}}}..., a:1 } Parenthetical: - obj = { ( body ), a:1 } - obj = { ( body )..., a:1 } Invocation: - obj = { ( (args) -> ... )(params), a:1 } - obj = { ( (args) -> ... )(params)..., a:1 } - obj = { foo(), a:1 } - obj = { foo()..., a:1 } 2. Refactor, cleanup & other optimizations. * Merged with 2.0 * Cleanup * Some more cleanup. * Fixed error with freeVariable and object destructuring. * Fixed errors with object spread properties. * Improvements, fixed errors. * Minor improvement. * Minor improvements. * Typo. * Remove unnecessary whitespace. * Remove unnecessary whitespace. * Changed few "assertErrorFormat" tests since parentheses are now allowed in the Obj. * Whitespace cleanup * Comments cleanup * fix destructured obj param declarations * refine fix; add test * Refactor function args ({a, b...}) * Additional tests for object destructuring in function argument. * Minor improvement for object destructuring variable declaration. * refactor function args ({a, b...}) and ({a, b...} = {}); Obj And Param cleanup * fix comment * Fix object destructuring variable declaration. * more tests with default values * fix typo * Fixed default values in object destructuring. * small fix * Babel’s tests for object rest spread * Style: spaces after colons in object declarations * Cleanup comments * Simplify Babel tests * Fix comments * Fix destructuring with splats in multiple objects * Add test for default values in detsructuring assignment with splats * Handle default values when assigning to object splats * Rewrite traverseRest to fix handling of dynamic keys * Fix double parens around destructuring with splats * Update compileObjectDestruct comments * Improve formatting of top-level destructures with splats and tidy parens * Added a bigger destructuring-with-defaults test and fixed a bug * Refactor destructuring grammar to allow additional forms * Add a missing case to ObjSpreadExpr * These tests shouldn’t run in the browser * Fix test.html * Fix docs scroll position getting screwed up by CodeMirror initialization * Breaking change documentation about => (fixes #4593) * Spread/rest syntax documentation * Documentation about bound class methods * 2.0.0-beta3 changelog * Add note about ‘lib’ * Fix accidentally converting this to tabs * Bump version to 2.0.0-beta3 * Update annotated source and test.html
2017-06-30 16:58:05 +00:00
<div id="array-spread" class="bookmark"></div>
Splats also let us elide array elements...
```
codeFor('array_spread', 'all')
```
<div id="object-spread" class="bookmark"></div>
...and object properties.
```
codeFor('object_spread', 'JSON.stringify(currentUser)')
```
In ECMAScript this is called [spread syntax](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator), and has been supported for arrays since ES2015 but is [coming soon for objects](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator#Spread_in_object_literals). Until object spread syntax is officially supported, the CoffeeScript compiler outputs the same polyfill as [Babel’s rest spread transform](https://babeljs.io/docs/plugins/transform-object-rest-spread/); but once it is supported, we will revise the compiler’s output. Note that there are [very subtle differences](https://developers.google.com/web/updates/2017/06/object-rest-spread) between the polyfill and the current proposal.