变量的字符串插值 [英] String interpolation on variable

问题描述

假设我有一个变量 str

var str = "123"

现在我可以执行 console.log(`Hello ${str}`) 并且它会打印 Hello 123

Now I could do console.log(`Hello ${str}`) and it will print Hello 123

现在我有另一个变量 strnew

var strnew = 'Hello ${str}'

注意(基于答案/评论) - strnew 是从文件中读取的，因此它始终是一个字符串并且不能用 `

Note (based on answers/comments) - strnew is read from a file, so its always a string and cant be replaced with `

我如何console.log(...) 打印Hello 123

是否有可能没有任何类型的 eval()

Is it possible wihtout any kind of eval()

推荐答案

使用像 ${str} 这样简单的东西，您可以使用简单的字符串替换:

With something as simple as ${str} you can use a simple string replacement:

var template = (tpl, args) => tpl.replace(/${(w+)}/g, (_, v) => args[v]);

var tpl = 'Hello ${str} and ${other}';

console.log(template(tpl, {str: 'foo', other: 'bar'}));

在一般情况下，不，不可能没有 eval(缺少编写自己的 js 解释器)，因为 ${...} 可以包含任意表达式.

In a general case, no, not possible without eval (short of writing your own js interpreter), because ${...} can contain arbitrary expressions.

为了完整起见，这里是 eval 解决方案:

For completeness' sake, here's the eval solution:

var template = function(tpl, args) {
    var keys = Object.keys(args),
        fn = new Function(...keys, 
          'return `' + tpl.replace(/`/g, '\`') + '`');
    return fn(...keys.map(x => args[x]));
};


function test() {
    var myTpl = 'Hello ${str + "!"} and ${other.toUpperCase()}';
    console.log(template(myTpl, {str: 'foo', other: 'bar'}));
}

test();

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