An optionally-asynchronous forEach with an interesting interface.
npm install async-foreachAn optionally-asynchronous forEach with an interesting interface.
This code should work just fine in Node.js:
First, install the module with: npm install async-foreach
``javascript`
var forEach = require('async-foreach').forEach;
forEach(["a", "b", "c"], function(item, index, arr) {
console.log("each", item, index, arr);
});
// logs:
// each a 0 ["a", "b", "c"]
// each b 1 ["a", "b", "c"]
// each c 2 ["a", "b", "c"]
Or in the browser:
`html`
In the browser, you can attach the forEach method to any object.
`html`
The idea is to allow the callback to decide _at runtime_ whether the loop will be synchronous or asynchronous. By using this in a creative way (in situations where that value isn't already spoken for), an entire control API can be offered without over-complicating function signatures.
`javascript
forEach(arr, function(item, index) {
// Synchronous.
});
forEach(arr, function(item, index) {
// Only when this.async is called does iteration becomes asynchronous. Thedone
// loop won't be continued until the function is executed.
var done = this.async();
// Continue in one second.
setTimeout(done, 1000);
});
forEach(arr, function(item, index) {
// Break out of synchronous iteration early by returning false.
return index !== 1;
});
forEach(arr, function(item, index) {
// Break out of asynchronous iteration early...
var done = this.async();
// ...by passing false to the done function.
setTimeout(function() {
done(index !== 1);
});
});
`
`javascript
// Generic "done" callback.
function allDone(notAborted, arr) {
console.log("done", notAborted, arr);
}
// Synchronous.
forEach(["a", "b", "c"], function(item, index, arr) {
console.log("each", item, index, arr);
}, allDone);
// logs:
// each a 0 ["a", "b", "c"]
// each b 1 ["a", "b", "c"]
// each c 2 ["a", "b", "c"]
// done true ["a", "b", "c"]
// Synchronous with early abort.
forEach(["a", "b", "c"], function(item, index, arr) {
console.log("each", item, index, arr);
if (item === "b") { return false; }
}, allDone);
// logs:
// each a 0 ["a", "b", "c"]
// each b 1 ["a", "b", "c"]
// done false ["a", "b", "c"]
// Asynchronous.
forEach(["a", "b", "c"], function(item, index, arr) {
console.log("each", item, index, arr);
var done = this.async();
setTimeout(function() {
done();
}, 500);
}, allDone);
// logs:
// each a 0 ["a", "b", "c"]
// each b 1 ["a", "b", "c"]
// each c 2 ["a", "b", "c"]
// done true ["a", "b", "c"]
// Asynchronous with early abort.
forEach(["a", "b", "c"], function(item, index, arr) {
console.log("each", item, index, arr);
var done = this.async();
setTimeout(function() {
done(item !== "b");
}, 500);
}, allDone);
// logs:
// each a 0 ["a", "b", "c"]
// each b 1 ["a", "b", "c"]
// done false ["a", "b", "c"]
// Not actually asynchronous.
forEach(["a", "b", "c"], function(item, index, arr) {
console.log("each", item, index, arr);
var done = this.async()
done();
}, allDone);
// logs:
// each a 0 ["a", "b", "c"]
// each b 1 ["a", "b", "c"]
// each c 2 ["a", "b", "c"]
// done true ["a", "b", "c"]
// Not actually asynchronous with early abort.
forEach(["a", "b", "c"], function(item, index, arr) {
console.log("each", item, index, arr);
var done = this.async();
done(item !== "b");
}, allDone);
// logs:
// each a 0 ["a", "b", "c"]
// each b 1 ["a", "b", "c"]
// done false ["a", "b", "c"]
``
_Also, please don't edit files in the "dist" subdirectory as they are generated via grunt. You'll find source code in the "lib" subdirectory!_
11/11/2011
v0.1.0
Initial Release.
11/11/2011
v0.1.1
Refactored code to be much simpler. Yay for unit tests!
11/17/2011
v0.1.2
Adding sparse array support.
Invalid length properties are now sanitized.
This closes issue #1 (like a boss).