64 lines
1.8 KiB
Plaintext
64 lines
1.8 KiB
Plaintext
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{{alias}}( x, y, done )
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If a function does not return an error, invokes a callback with the function
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result; otherwise, invokes a callback with a value `y`.
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A function `x` is provided a single argument:
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- clbk: callback to invoke upon function completion
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The callback function accepts two arguments:
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- error: error object
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- result: function result
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The `done` callback is invoked upon function completion and is provided two
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arguments:
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- error: error object
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- result: either the result of `x` or the provided argument `y`
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If `x` invokes `clbk` with an error argument, the function invokes the
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`done` callback with both the error and the argument `y`.
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If `x` does not invoke `clbk` with an error argument, the function invokes
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the `done` callback with a first argument equal to `null` and the function
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`result`.
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Execution is *not* guaranteed to be asynchronous. To guarantee asynchrony,
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wrap the `done` callback in a function which either executes at the end of
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the current stack (e.g., `nextTick`) or during a subsequent turn of the
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event loop (e.g., `setImmediate`, `setTimeout`).
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Parameters
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----------
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x: Function
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Function to invoke.
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y: any
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Value to return if `x` returns an error.
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done: Function
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Callback to invoke upon completion.
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Examples
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--------
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> function x( clbk ) {
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... setTimeout( onTimeout, 0 );
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... function onTimeout() {
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... clbk( new Error( 'beep' ) );
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... }
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... };
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> function done( error, result ) {
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... if ( error ) {
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... // process error...
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... }
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... console.log( result );
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... };
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> {{alias}}( x, 'boop', done )
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'boop'
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See Also
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--------
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