6 lines
1.5 KiB
Markdown
6 lines
1.5 KiB
Markdown
### Named functions and function declarations
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Newcomers to CoffeeScript often wonder how to generate the JavaScript `function foo() {}`, as opposed to the `foo = function() {}` that CoffeeScript produces. The first form is a [function declaration](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function), and the second is a [function expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/function). As stated above, in CoffeeScript [everything is an expression](#expressions), so naturally we favor the expression form. Supporting only one variant helps avoid confusing bugs that can arise from the [subtle differences between the two forms](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function#Function_declaration_hoisting).
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Technically, `foo = function() {}` is creating an anonymous function that gets assigned to a variable named `foo`. Some very early versions of CoffeeScript named this function, e.g. `foo = function foo() {}`, but this was dropped because of compatibility issues with Internet Explorer. For a while this annoyed people, as these functions would be unnamed in stack traces; but modern JavaScript runtimes [infer the names of such anonymous functions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/name) from the names of the variables to which they’re assigned. Given that this is the case, it’s simplest to just preserve the current behavior.
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