Regular Expression to replace arithmetic operators in Javascript

Question

I have an array of string that contains arithmetic operators and I would like to replace those arithmetic operators in the array with a new arithmetic operator.

For instance:

var equation = '5.0 + 9.34 - 6.0 * 2.1 * 3.1 / 2.0';

var newEquation = equation.replace(/+-*//, '+');

However, it does not change to the wanted result. Please advise. Your contribution is much appreciated.

That's not an array. It's just a string literal.

Andrew Li
– Andrew Li

2016-06-14 04:16:12 +00:00
Commented Jun 14, 2016 at 4:16 — Andrew Li
– Andrew Li, Commented Jun 14, 2016 at 4:16

Pranav C Balan · Accepted Answer · 2016-06-14 05:10:12Z

7

Use character class([])

var equation = '5.0 + 9.34 - 6.0 * 2.1 * 3.1 / 2.0';

var newEquation = equation.replace(/[+*\/-]/g, '+');
// or : equation.replace(/[+\-*/]/g, '+');

console.log(newEquation);

UPDATE : For avoiding negative numbers use negative look-ahead assertion and capturing group.

var equation = '-5.0 + 9.34 - 6.0 * -2.1 * 3.1 / -2.0';

var newEquation = equation.replace(/(?!^-)[+*\/-](\s?-)?/g, '+$1');

console.log(newEquation);

Regex explanation here

Regular expression visualization

edited Jun 14, 2016 at 5:10

answered Jun 14, 2016 at 4:16

Pranav C Balan

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3 Comments

Clay Over a year ago

Thank you for your contribution @Pranav Is there a way to differentiate from a negative number? For instance: '-5.0 + 9.34 - -6.0'

Clay Over a year ago

Thank you @Pranav. Much appreciated!

Pranav C Balan Over a year ago

@Clay : glad to help :)

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