regex to replace two separate things separately in one replace [duplicate]

Question

I need to replace 1 with a 0, and replace 0 with 1 in a string. I know how to replace one thing with another, but how can I replace two separately. See the attempt below.

const broken = str => {
  return str.replace(/1/g, '0').replace(/0/g, '1');
}

This is an example:

input

011101

output

100010

I know I could do it in 2 stages Wouldn't work like that, then all 0s and 1s would be turned into 1s — CertainPerformance
– CertainPerformance, Commented Oct 20, 2018 at 20:29
@CertainPerformance you are dead right, I probably shouldn't have said that and only realised when I tried it :-D — peter flanagan
– peter flanagan, Commented Oct 20, 2018 at 20:29

Nina Scholz · Accepted Answer · 2018-10-20 20:29:43Z

1

You could take a function and an object for taking the replacement value.

const broken = str => str.replace(/[01]/g, match => ({ 0: 1, 1: 0 }[match]));

console.log(broken('1100'));

edited Oct 20, 2018 at 20:29

answered Oct 20, 2018 at 20:28

Nina Scholz

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4 Comments

peter flanagan Over a year ago

what does the m mean?

Nina Scholz Over a year ago

it is the matched value.

str Over a year ago

This is exactly the same principle as in the duplicate question.

CertainPerformance Over a year ago

Another option which will work only in this particular situation would be to subtract from 1: match => 1 - match :)

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