JS字符串拼接对比

看不同的插件代码，看到不一样的字符串拼接方式，(1)很多是 ['str1', 'str2'].join('')搞的，(2)也有一些是 ‘+’ 直接拼接的，具体到我自己写的时候，我也是什么都写过，(3)用反斜杠 ‘\’都写过，后来用 eslinter后发现，它不建议这么写，说是以后的规范(eg: ES6等)可能不支持这种写法了，(4)也发现还可以用反撇号 ` 包起来，哎，总之很多种…

High-performance String Concatenation in JavaScript

Do you wanna test it?

The first uses the string concatenation operator:

// standard string append
var str = "";
for (var i = 30000; i > 0; i--) {
    str += "String concatenation. ";
}

The second uses an array join:

// array join
var str = "", sArr = [];
for (var i = 30000; i > 0; i--) {
    sArr[i] = "String concatenation. ";
}
str = sArr.join("");

The truth is rather more complex.

• Chrome 6.0: standard string appends are usually quicker than array joins, but both complete in less than 10ms.
• Opera 10.6: again, standard appends are quicker, but the difference is marginal—often 15ms compared to 17ms for an array join.
• Firefox 3.6: the browser normally takes around 30ms for either method. Array joins usually have the edge, but only by a few milliseconds.
• IE 8.0: a standard append requires 30ms, whereas an array join is more than double—typically 70ms.
• Safari 5.0.1: bizarrely, a standard append takes no more than 5ms but an array join is more than ten times slower at 55ms.

• IE7: If you’re supporting IE7, array joins remain the best method for concatenating a large number of strings.