javascript js - 检查一个函数是否完成
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js - check if a function is completed
提问by Lewis
I want to set a hotkey to several functions by jquery hotkeys. And I need to check if a function is finished, may be something like:
我想通过 jquery 热键为几个功能设置一个热键。我需要检查一个函数是否完成，可能是这样的：
if("function A is completed")
{
"Ctrl+A is now set to function B"
}
else
{
"Ctrl+A is set to function A"
}
How could I check this? Or any better ideas?
我怎么能检查这个？或者有什么更好的想法？
采纳答案by T.J. Crowder
JavaScript on web browsers is single-threaded (barring the use of web workers, and even with those a function can't be interrupted), so except for a couple of bugs inissueswith Firefox, a function cannotbe interrupted in the middle. So if your code is running, the other function is not, by definition.
的JavaScript的Web浏览器是单线程（禁止使用网络工作者，甚至与那些功能不能中断），所以除了几个中的错误问题与Firefox，功能不能在中途中断。因此，如果您的代码正在运行，那么根据定义，另一个函数不会运行。
(For details on the issues with Firefox, see this answer by bobinceabout some very edge-case scenarios.)
回答by Zanderi
Depending on the situation there are a couple of things you can do. You can call the function when you've finished completing the current function or you can set a boolean for the same thing.
根据具体情况，您可以做几件事。您可以在完成当前函数后调用该函数，也可以为同一事物设置一个布尔值。
function A(){
alert('run items in function A');
return fireNewFunctionWhenComplete()
}
or set a flag
或设置一个标志
/*global var*/
var functionBCompleted = false;
function B(){
alert('run items in function B');
return functionBCompleted = true;
}
function testFunctionComplete(){
if(functionBCompleted){
alert('function B Copmleted');
}
else{
alert('function B not run');
}
}
This is a very simple example and as @T.J. mentioned you can't interrupt a running process. However, you may want to take a look into the promises spec if you want to run something when an asynchronous operation has completed.
这是一个非常简单的例子，正如@TJ 提到的，你不能中断正在运行的进程。但是，如果您想在异步操作完成后运行某些内容，您可能需要查看 promise 规范。
