javascript 获取 SetTimeout 后的返回值
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Get return value after SetTimeout
提问by Max Frai
I've just asked about calling functions by name, now I want to process returnstatement after SetTimeout:
我刚刚询问了按名称调用函数的问题，现在我想在以下之后处理return语句SetTimeout：
function ECall(funcName, arg)
{
command += "(";
for (var i=1; i<arguments.length; i++)
{
command += "'" + arguments[i] + "'";
if (i != arguments.length-1) command += ',';
}
command += ")";
//var funcPtr = eval(funcName);
//return funcPtr(arg); // This works, but I need SetTimeout
setTimeout('window[\'' + funcName + '\']' + command, 1000);
}
setTimeoutworks great, but I have to save return value of called function. When I write: setTimeout('alert(window[\'' + funcName + '\']' + command + ')', 1000);It alerts return value of function. How can I store it?
setTimeout效果很好，但我必须保存被调用函数的返回值。当我写：setTimeout('alert(window[\'' + funcName + '\']' + command + ')', 1000);它提醒函数的返回值。我怎样才能储存它？
采纳答案by Tim Down
You don't need to use any of this string manipulation. Just pass a function reference to window.setTimeout(). To store the returned value of the function, simply assign it to a variable in the function you pass to window.setTimeout()
您不需要使用任何这种字符串操作。只需将函数引用传递给window.setTimeout(). 要存储函数的返回值，只需将其分配给传递给的函数中的变量window.setTimeout()
var savedValue;
function ECall(funcName)
{
var args = Array.prototype.slice.call(arguments, 1);
var func = window[funcName];
window.setTimeout(function() {
savedValue = func.apply(this, args);
}, 1000);
}
回答by user113716
If you wanted to return a value from ECall, it won't work.
如果您想从 返回一个值ECall，它将不起作用。
The setTimeoutis asynchronous, which means that the ECallwill return beforethe setTimeoutcode is invoked.
该setTimeout是异步的，这意味着ECall将返回之前的setTimeout调用代码。
Or if you wanted the alert()to be part of the setTimeout, you could pass an anonymous function. Also, it would be better to not pass a string to the setTimeout.
或者，如果您希望alert()成为 的一部分，则setTimeout可以传递一个匿名函数。此外，最好不要将字符串传递给setTimeout.
I'd do this instead:
我会这样做：
function ECall(funcName, arg)
{
// Get an Array of the arguments, except for the first one.
var args = Array.prototype.slice.call( arguments, 1 );
// Pass an anonymous function that calls the global "funcName" function
// inside the alert().
// It uses .apply() to pass the arguments we sliced.
setTimeout( function() {
alert( window[ funcName ].apply( window, args ) );
}, 1000);
}
