如何使用 jQuery .When .done
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/15594567/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to use jQuery .When .done
提问by Philip Kirkbride
I'm trying to run one function after another function completes.
我试图在另一个函数完成后运行一个函数。
$.when(saveCanvas(canvas)).done(setWallPaper());
Each function works fine on it's own but when I run the code above it only runs the first function.
每个函数都可以正常工作，但是当我运行上面的代码时，它只运行第一个函数。
What do I need to change?
我需要改变什么？
采纳答案by Philip Kirkbride
Looking back at this now, this seems to be how it works with jQuery:
现在回头看，这似乎是它与 jQuery 的工作方式：
function f1() {
alert("function one");
}
$.when( f1() ).done(function() {
alert("function 1 is done running function two");
});<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>Note: This is identical to my method I posted in the question so essentially it should have worked. Though jQuery may have changed over the last 3 years. Most likely was a problem with functions being called.
注意：这与我在问题中发布的方法相同，因此基本上它应该有效。尽管 jQuery 在过去 3 年中可能发生了变化。很可能是调用函数的问题。
回答by Luke Shaheen
According to a comment on another SO question, $.whenexpects deferred objects as arguments. If you don't pass anything, the callbacks will be invoked immediately.
根据对另一个 SO 问题的评论，$.when期望延迟对象作为参数。如果你不传递任何东西，回调将被立即调用。
Does setWallPaper()appear to not be working because it is actually being run before saveCancas(canvas)? saveCanvas()is not actually a deferred object, which whenexpects it to be. To make it a deferred object, add dfr = $.Deferred();to the beginning of your saveCanvas()function and return dfr.promise();to the end of it. Check out this SO answerfor more details.
难道setWallPaper()看起来不工作，因为它实际上是被之前运行saveCancas(canvas)？saveCanvas()实际上不是延迟对象，它when期望它是。要使其成为延迟对象，请添加dfr = $.Deferred();到saveCanvas()函数的开头和return dfr.promise();结尾。查看此 SO 答案以获取更多详细信息。
function saveCanvas(canvas)
{
dfr = $.Deferred();
//Your code
return dfr.promise();
}
Read more: http://api.jquery.com/jQuery.when/
回答by Crash Override
another wild guess:
另一个疯狂的猜测：
$.when(saveCanvas(canvas)).done(function(){
setWallPaper()
});
