将字符串计算为 JavaScript 中的数学表达式 [英] Evaluating a string as a mathematical expression in JavaScript

问题描述

如何在不调用 eval(string) 的情况下解析和评估字符串中的数学表达式(例如 '1+1')以产生其数值?

How do I parse and evaluate a mathematical expression in a string (e.g. '1+1') without invoking eval(string) to yield its numerical value?

在这个例子中，我希望函数接受 '1+1' 并返回 2.

With that example, I want the function to accept '1+1' and return 2.

推荐答案

我最终选择了这个解决方案，它适用于对正整数和负整数求和(对正则表达式稍作修改也适用于小数):

I've eventually gone for this solution, which works for summing positive and negative integers (and with a little modification to the regex will work for decimals too):

function sum(string) {
  return (string.match(/^(-?d+)(+-?d+)*$/)) ? string.split('+').stringSum() : NaN;
}   

Array.prototype.stringSum = function() {
    var sum = 0;
    for(var k=0, kl=this.length;k<kl;k++)
    {
        sum += +this[k];
    }
    return sum;
}

我不确定它是否比 eval() 快，但由于我必须多次执行该操作，因此运行此脚本比创建大量 javascript 编译器实例更舒服

I'm not sure if it's faster than eval(), but as I have to carry out the operation lots of times I'm far more comfortable runing this script than creating loads of instances of the javascript compiler

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