使用 jQuery.each() 时返回一个值？
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Return a value when using jQuery.each()?
提问by Prashant Lakhlani
I want to return false and return from function if I find first blank textbox
如果我找到第一个空白文本框，我想返回 false 并从函数返回
function validate(){
$('input[type=text]').each(function(){
if($(this).val() == "")
return false;
});
}
and above code is not working for me :( can anybody help?
上面的代码对我不起作用:(有人可以帮忙吗？
回答by Nick Craver
You are jumping out, but from the innerloop, I would instead use a selector for your specific "no value" check, like this:
您正在跳出，但是从内部循环中，我会改为使用选择器进行特定的“无值”检查，如下所示：
function validate(){
if($('input[type=text][value=""]').length) return false;
}
Or, set the result as you go inside the loop, and return thatresult from the outer loop:
或者，在循环内部设置结果，并从外部循环返回该结果：
function validate() {
var valid = true;
$('input[type=text]').each(function(){
if($(this).val() == "") //or a more complex check here
return valid = false;
});
return valid;
}
回答by T.J. Crowder
You can do it like this:
你可以这样做：
function validate(){
var rv = true;
$('input[type=text]').each(function(){
if($(this).val() == "") {
rv = false; // Set flag
return false; // Stop iterating
}
});
return rv;
}
That assumes you want to return trueif you don't find it.
假设您true没有找到它就想返回。
You may find that this is one of those sitautions where you don't want to use eachat all:
您可能会发现这是您根本不想使用的each情况之一：
function validate(){
var inputs = $('input[type=text]');
var index;
while (index = inputs.length - 1; index >= 0; --index) {
if (inputs[index].value == "") { // Or $(inputs[index]).val() == "" if you prefer
return false;
}
}
// (Presumably return something here, though you weren't in your example)
}
回答by Mr.Hunt
I want to add something to existing answers to clear the behavior of $(selector).eachand why it doesn't respect return false in OP's code.
我想在现有答案中添加一些内容，以清除$(selector).eachOP 代码中的行为以及为什么它不尊重 return false 。
returnkeyword inside $(selector).eachis used to break or continue the loop. If you use return false, it is equivalent to a breakstatement inside a for/whileloop. Returning non-false is the same as a continuestatement in a forloop; it will skip immediately to the next iteration. Source
return关键字 inside$(selector).each用于中断或继续循环。如果使用return false，则相当于循环break内的语句for/while。返回非假与循环中的continue语句相同for；它将立即跳到下一次迭代。来源
Because you're returning false, the loop breaks and the function ends up returning undefinedin your case.
Your option is to use a var outside $.eachor avoid using it altogether as @TJCrowder wrote.
因为您返回 false，所以循环中断并且函数最终undefined在您的情况下返回。您的选择是在外部使用 var$.each或避免像@TJCrowder 所写的那样完全使用它。
