在JavaScript中将字符串作为数学表达式进行评估(Evaluating a string as a mathematical expression in JavaScript)

在JavaScript中将字符串作为数学表达式进行评估(Evaluating a string as a mathematical expression in JavaScript)

如何解析和评估字符串中的数学表达式（例如'1+1' ），而不调用eval(string)以产生其数值？

有了这个例子，我希望函数接受'1+1'并返回2 。

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?

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

最满意答案

您可以使用JavaScript Expression Evaluator库 ，它可以让您执行以下操作：

Parser.evaluate("2 ^ x", { x: 3 });

或者mathjs ，它允许的东西像：

math.eval('sin(45 deg) ^ 2');

我最终选择了我的一个项目的mathjs。

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; }

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