Javascript 将文本添加到字符串的开头

Prepend text to beginning of string

提问by mate64

What is the fastest method, to add a new value at the beginning of a string?

在字符串的开头添加新值的最快方法是什么？

回答by Thor Jacobsen

var mystr = "Doe";
mystr = "John " + mystr;

Wouldn't this work for you?

这不适合你吗？

回答by Gabriele Petrioli

You could do it this way ..

你可以这样做..

var mystr = 'is my name.';
mystr = mystr.replace (/^/,'John ');

console.log(mystr);

disclaimer: http://xkcd.com/208/

免责声明：http: //xkcd.com/208/

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回答by KyleMit

Since the question is about what is the fastestmethod, I thought I'd throw up add some perf metrics.

由于问题是关于最快的方法是什么，我想我会抛出添加一些性能指标。

TL;DRThe winner, by a wide margin, is the +operator, and pleasenever use regex

TL;DR赢家，以较大的优势，是+运营商，请永远不要使用正则表达式

https://jsperf.com/prepend-text-to-string/1

https://jsperf.com/prepend-text-to-string/1

回答by Griffi

ES6:

ES6：

let after = 'something after';
let text = `before text ${after}`;

回答by chirag

you could also do it this way

你也可以这样做

"".concat("x","y")

回答by Ilan Schemoul

If you want to use the version of Javascript called ES 2015 (aka ES6) or later, you can use template stringsintroduced by ES 2015 and recommended by some guidelines (like Airbnb's style guide):

如果您想使用名为 ES 2015（又名 ES6）或更高版本的 Javascript，您可以使用ES 2015 引入的模板字符串，并由一些指南（如Airbnb 的样式指南）推荐：

const after = "test";
const mystr = `This is: ${after}`;

回答by MatayoshiMariano

Another option would be to use join

另一种选择是使用join

var mystr = "Matayoshi";
mystr = ["Mariano", mystr].join(' ');

回答by Mayank

You can use

您可以使用

var mystr = "Doe";
mystr = "John " + mystr;
console.log(mystr)