在JavaScript中将字符串评估为数学表达式 [英] Evaluating a string as a mathematical expression in JavaScript
问题描述
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)
产生它的数值?
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
我最终为这个解决方案而去,它可用于求和正整数和负整数(并且对正则表达式进行一些修改也适用于小数):
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()更快,但是因为我必须多次执行操作我运行这个脚本比创建javascript编译器的大量实例更加舒服
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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