我应该修改String的原型吗? [英] Should i modify the prototype of String?

问题描述

我正准备在 javascript 中创建一个修剪函数，但由于我不想重新发明轮子，所以我用谷歌搜索了这个方法.
我找到了这个链接http://www.somacon.com/p355.php

I was about to create a trim function in javascript, but as i don't want to reinvent the wheel i googled for this method.
I found this link http://www.somacon.com/p355.php

它提供的解决方案是:

String.prototype.trim = function() {
    return this.replace(/^\s+|\s+$/g,"");
}
String.prototype.ltrim = function() {
    return this.replace(/^\s+/,"");
}
String.prototype.rtrim = function() {
    return this.replace(/\s+$/,"");
}

还说如果你不想改变 String 的原型，那么使用这个:

also it says if you don'y wnt to change the prototype of String then use this:

function trim(stringToTrim) {
    return stringToTrim.replace(/^\s+|\s+$/g,"");
}
function ltrim(stringToTrim) {
    return stringToTrim.replace(/^\s+/,"");
}
function rtrim(stringToTrim) {
    return stringToTrim.replace(/\s+$/,"");
}

我想知道在什么情况下应该不修改String的原型或者说任何对象.

I would like to know in what scenario one should not modify the prototype of String or say any object.

推荐答案

trim 函数将在 ECMAScript 第五版中标准化，并且已经存在于某些浏览器中.所以:

The trim functions are to be standardised in ECMAScript Fifth Edition, as well as already being present in some browsers. So:

1. 是的，将它们添加到原型中是完全合适的，但是

1. Yes, adding them to the prototype is totally appropriate, but

如果它们已经存在，您不应该将它们添加到原型中，因为您只会用慢速 JavaScript 函数替换快速的本机代码函数.

You shouldn't add them to the prototype if they're already there, as you'll just be replacing a fast native-code function with a slow JavaScript one.

作为两个替换进行修剪通常也稍微快一点:

It is also typically marginally faster to do trim as two replaces:

// Add ECMA262-5 string trim if not supported natively
//
if (!('trim' in String.prototype)) {
    String.prototype.trim= function() {
        return this.replace(/^\s+/, '').replace(/\s+$/, '');
    };
}

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