如何在 Javascript 中使用正则表达式不拆分数学方程字符串中的小数点

Question

I have this string that contain Math equation. And I want to split it based on the operator between number. Because later I want to use it with eval() to do math operation.

Like this:

var myString = "25+15-10/555"
var newString = myString.split(/([x+-/])/).filter(Boolean);

Which I have successfully split the string like I want:

output: ["25", "+", "15", "-", "10", "/", "555"]

The problem is If I have decimal point in my string. It will separate a number that actually a decimal point number:

var myString = "2.5+15-55.50"
var newString = myString.split(/([x+-/])/).filter(Boolean);

output: ["2", ".", "5", "+", "15", "-", "55", ".", "50"]

As you can see, it separate 2.5 and 55.50 . How can I achieve this output: ["2.5", "+", "15", "-", "55.50"] ?

What should I do to my Regex? Or maybe there's something wrong with it?

Answer 1

You almost had the correct regex, problem with /([x+-/])/ is that the minus sign is interpreted as a range specifier in the character class, in this case indicating from plus (+) to slash (/). What you could do is either escape the minus sign with a backslash:

/([x+\-/])/

Or move it to the end of the character class:

/([x+/-])/

Answer 2

It's because - in your characters list acts as range operator and has meaning all characters between from "+" till "/" (similar to [az] .

Move it to end of list or escape:

 var myString = "2.5+15-55.50" console.log(myString.split(/([x+\-/])/));