58 lines
2.1 KiB
JavaScript
58 lines
2.1 KiB
JavaScript
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/* JavaScript Sync/Async forEach - v0.1.2 - 1/10/2012
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* http://github.com/cowboy/javascript-sync-async-foreach
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* Copyright (c) 2012 "Cowboy" Ben Alman; Licensed MIT */
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(function(exports) {
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// Iterate synchronously or asynchronously.
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exports.forEach = function(arr, eachFn, doneFn) {
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var i = -1;
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// Resolve array length to a valid (ToUint32) number.
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var len = arr.length >>> 0;
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// This IIFE is called once now, and then again, by name, for each loop
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// iteration.
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(function next(result) {
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// This flag will be set to true if `this.async` is called inside the
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// eachFn` callback.
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var async;
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// Was false returned from the `eachFn` callback or passed to the
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// `this.async` done function?
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var abort = result === false;
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// Increment counter variable and skip any indices that don't exist. This
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// allows sparse arrays to be iterated.
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do { ++i; } while (!(i in arr) && i !== len);
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// Exit if result passed to `this.async` done function or returned from
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// the `eachFn` callback was false, or when done iterating.
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if (abort || i === len) {
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// If a `doneFn` callback was specified, invoke that now. Pass in a
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// boolean value representing "not aborted" state along with the array.
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if (doneFn) {
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doneFn(!abort, arr);
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}
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return;
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}
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// Invoke the `eachFn` callback, setting `this` inside the callback to a
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// custom object that contains one method, and passing in the array item,
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// index, and the array.
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result = eachFn.call({
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// If `this.async` is called inside the `eachFn` callback, set the async
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// flag and return a function that can be used to continue iterating.
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async: function() {
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async = true;
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return next;
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}
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}, arr[i], i, arr);
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// If the async flag wasn't set, continue by calling `next` synchronously,
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// passing in the result of the `eachFn` callback.
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if (!async) {
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next(result);
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}
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}());
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};
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}(typeof exports === "object" && exports || this));
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