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setImmediate & startsWith shim
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if (!String.prototype.startsWith) { | |
String.prototype.startsWith = function (searchString, position) { | |
position = position || 0; | |
return this.lastIndexOf(searchString, position) === position; | |
}; | |
} | |
(function (global, undefined) { | |
"use strict"; | |
if (global.setImmediate) { | |
return; | |
} | |
var nextHandle = 1; // Spec says greater than zero | |
var tasksByHandle = {}; | |
var currentlyRunningATask = false; | |
var doc = global.document; | |
var setImmediate; | |
function addFromSetImmediateArguments(args) { | |
tasksByHandle[nextHandle] = partiallyApplied.apply(undefined, args); | |
return nextHandle++; | |
} | |
// This function accepts the same arguments as setImmediate, but | |
// returns a function that requires no arguments. | |
function partiallyApplied(handler) { | |
var args = [].slice.call(arguments, 1); | |
return function() { | |
if (typeof handler === "function") { | |
handler.apply(undefined, args); | |
} else { | |
(new Function("" + handler))(); | |
} | |
}; | |
} | |
function runIfPresent(handle) { | |
// From the spec: "Wait until any invocations of this algorithm started before this one have completed." | |
// So if we're currently running a task, we'll need to delay this invocation. | |
if (currentlyRunningATask) { | |
// Delay by doing a setTimeout. setImmediate was tried instead, but in Firefox 7 it generated a | |
// "too much recursion" error. | |
setTimeout(partiallyApplied(runIfPresent, handle), 0); | |
} else { | |
var task = tasksByHandle[handle]; | |
if (task) { | |
currentlyRunningATask = true; | |
try { | |
task(); | |
} finally { | |
clearImmediate(handle); | |
currentlyRunningATask = false; | |
} | |
} | |
} | |
} | |
function clearImmediate(handle) { | |
delete tasksByHandle[handle]; | |
} | |
function installNextTickImplementation() { | |
setImmediate = function() { | |
var handle = addFromSetImmediateArguments(arguments); | |
process.nextTick(partiallyApplied(runIfPresent, handle)); | |
return handle; | |
}; | |
} | |
function canUsePostMessage() { | |
// The test against `importScripts` prevents this implementation from being installed inside a web worker, | |
// where `global.postMessage` means something completely different and can't be used for this purpose. | |
if (global.postMessage && !global.importScripts) { | |
var postMessageIsAsynchronous = true; | |
var oldOnMessage = global.onmessage; | |
global.onmessage = function() { | |
postMessageIsAsynchronous = false; | |
}; | |
global.postMessage("", "*"); | |
global.onmessage = oldOnMessage; | |
return postMessageIsAsynchronous; | |
} | |
} | |
function installPostMessageImplementation() { | |
// Installs an event handler on `global` for the `message` event: see | |
// * https://developer.mozilla.org/en/DOM/window.postMessage | |
// * http://www.whatwg.org/specs/web-apps/current-work/multipage/comms.html#crossDocumentMessages | |
var messagePrefix = "setImmediate$" + Math.random() + "$"; | |
var onGlobalMessage = function(event) { | |
if (event.source === global && | |
typeof event.data === "string" && | |
event.data.indexOf(messagePrefix) === 0) { | |
runIfPresent(+event.data.slice(messagePrefix.length)); | |
} | |
}; | |
if (global.addEventListener) { | |
global.addEventListener("message", onGlobalMessage, false); | |
} else { | |
global.attachEvent("onmessage", onGlobalMessage); | |
} | |
setImmediate = function() { | |
var handle = addFromSetImmediateArguments(arguments); | |
global.postMessage(messagePrefix + handle, "*"); | |
return handle; | |
}; | |
} | |
function installMessageChannelImplementation() { | |
var channel = new MessageChannel(); | |
channel.port1.onmessage = function(event) { | |
var handle = event.data; | |
runIfPresent(handle); | |
}; | |
setImmediate = function() { | |
var handle = addFromSetImmediateArguments(arguments); | |
channel.port2.postMessage(handle); | |
return handle; | |
}; | |
} | |
function installReadyStateChangeImplementation() { | |
var html = doc.documentElement; | |
setImmediate = function() { | |
var handle = addFromSetImmediateArguments(arguments); | |
// Create a <script> element; its readystatechange event will be fired asynchronously once it is inserted | |
// into the document. Do so, thus queuing up the task. Remember to clean up once it's been called. | |
var script = doc.createElement("script"); | |
script.onreadystatechange = function () { | |
runIfPresent(handle); | |
script.onreadystatechange = null; | |
html.removeChild(script); | |
script = null; | |
}; | |
html.appendChild(script); | |
return handle; | |
}; | |
} | |
function installSetTimeoutImplementation() { | |
setImmediate = function() { | |
var handle = addFromSetImmediateArguments(arguments); | |
setTimeout(partiallyApplied(runIfPresent, handle), 0); | |
return handle; | |
}; | |
} | |
// If supported, we should attach to the prototype of global, since that is where setTimeout et al. live. | |
var attachTo = Object.getPrototypeOf && Object.getPrototypeOf(global); | |
attachTo = attachTo && attachTo.setTimeout ? attachTo : global; | |
// Don't get fooled by e.g. browserify environments. | |
if ({}.toString.call(global.process) === "[object process]") { | |
// For Node.js before 0.9 | |
installNextTickImplementation(); | |
} else if (canUsePostMessage()) { | |
// For non-IE10 modern browsers | |
installPostMessageImplementation(); | |
} else if (global.MessageChannel) { | |
// For web workers, where supported | |
installMessageChannelImplementation(); | |
} else if (doc && "onreadystatechange" in doc.createElement("script")) { | |
// For IE 6–8 | |
installReadyStateChangeImplementation(); | |
} else { | |
// For older browsers | |
installSetTimeoutImplementation(); | |
} | |
attachTo.setImmediate = setImmediate; | |
attachTo.clearImmediate = clearImmediate; | |
}(new Function("return this")())); |
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