76 lines
2.3 KiB
Plaintext
76 lines
2.3 KiB
Plaintext
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{{alias}}( fcn, predicate, done[, thisArg] )
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Invokes a function while a test condition is true.
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The condition is evaluated *after* executing the provided function; thus,
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`fcn` *always* executes at least once.
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The function to invoke is provided two arguments:
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- `i`: iteration number (starting from zero)
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- `next`: a callback which must be invoked before proceeding to the next
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iteration
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The first argument of the `next` callback is an `error` argument. If `fcn`
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calls the `next` callback with a truthy `error` argument, the function
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suspends execution and immediately calls the `done` callback for subsequent
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`error` handling.
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The predicate function is provided two arguments:
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- `i`: iteration number (starting from one)
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- `clbk`: a callback indicating whether to invoke `fcn`
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The `clbk` function accepts two arguments:
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- `error`: error argument
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- `bool`: test result
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If the test result is truthy, the function continues invoking `fcn`;
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otherwise, the function invokes the `done` callback.
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The `done` callback is invoked with an `error` argument and any arguments
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passed to the final `next` callback.
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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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fcn: Function
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The function to invoke.
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predicate: Function
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The predicate function which indicates whether to continue invoking a
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function.
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done: Function
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Callback to invoke upon completion.
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thisArg: any (optional)
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Execution context for the invoked function.
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Examples
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--------
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> function fcn( i, next ) {
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... setTimeout( onTimeout, i );
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... function onTimeout() {
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... next( null, 'boop'+i );
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... }
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... };
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> function predicate( i, clbk ) { clbk( null, i < 5 ); };
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> function done( error, result ) {
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... if ( error ) {
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... throw error;
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... }
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... console.log( result );
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... };
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> {{alias}}( fcn, predicate, done )
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boop: 4
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See Also
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--------
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