Javascript 如何使用 jQuery 的 trim() 函数
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How to use jQuery's trim() function
提问by Gideon
As discussed in many questions on stack - IE 8 wont accept .trim(), but the jQuery framework takes care of that.
正如许多关于堆栈的问题所讨论的那样 - IE 8 不会接受.trim()，但 jQuery 框架会处理这个问题。
I don't know how to translate my function to use that version of trim (I thought I was already using jQuery), could someone advise? Here is my code:
我不知道如何翻译我的函数以使用那个版本的修剪（我以为我已经在使用 jQuery），有人可以建议吗？这是我的代码：
$('input').val(function(index, val){
return val.replace('Please Select', '').trim();
});
This is designed to replace the string with nothing.
这旨在用空替换字符串。
I've tried:
我试过了：
$('input').val(function(index, val){
return val.replace('Please Select', '')$.trim();
});
but that was no good.
但这并不好。
回答by Tetaxa
$.trim(val.replace('Please Select', ''))
回答by Elias Van Ootegem
IE8 doesn't have a native trimmethod, generally, I just augment the prototype:
IE8没有原生trim方法，一般我只是增加原型：
if (!String.prototype.trim)
{
String.prototype.trim = function()
{
return this.replace(/^\s+|\s+$/g,'');
};
}
This is the shortest regex to trim a string, but I have heard it say that .replace(/^\s\s*/,'').replace(/\s*\s$/,'')is (marginally) faster... the choice is yours
这是修剪字符串的最短正则表达式，但我听说它.replace(/^\s\s*/,'').replace(/\s*\s$/,'')（略微）更快......选择是你的
If you really want to use jQuery for this, of course, you'll have to make the target string the context of the called method ($.trimcalls the method on $=== the jQuery object), so make the String a jQ object:
如果您真的想为此使用 jQuery，当然，您必须使目标字符串成为被调用方法的上下文（$.trim在$=== jQuery 对象上调用该方法），因此将 String 设为 jQ 对象：
$(' foo bar ').trim();//returns "foo bar"
//compared to augmented prototype:
' foo bar '.trim();//returns "foo bar"
The benefit of an augmented prototype is that you don't have the additional overhead of creating a new jQuery object, whereas using the prototype-approach relies on JS to wrap the string in a native String object and apply the method to that. Basically, it's the same operation, but it shouldbe a marginally more efficient, because jQuery does a bunch of checks to any string passed to the jQuery constructor ($())
增强原型的好处是您没有创建新 jQuery 对象的额外开销，而使用原型方法依赖于 JS 将字符串包装在本机 String 对象中并将方法应用于该对象。基本上，它是相同的操作，但它的效率应该略高一些，因为 jQuery 对传递给 jQuery 构造函数 ( $()) 的任何字符串进行大量检查
