How to convert this Regex with lookbehind so it works in Safari?

November 27, 2021

This Regex works fine in Chrome and Firefox

let regexp = new RegExp(`^${searchTerm}|(?<=\\s)${searchTerm}`, 'gi')

but unfortunately Safari complains

SyntaxError: Invalid regular expression: invalid group specifier name

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It looks like Safari doesn’t support the lookbehind, but how can I transform it so I get the indices of the searchTerm without the whitespaces?

let regexp = new RegExp(`^${searchTerm}|(?<=\\s)${searchTerm}`, 'gi')
let matchIndices = [...string.matchAll(regexp)].map(match => match.index);

matchIndices.forEach(index => {
   ...
});

>Solution :

You can use a regex like /(^|\s)word/gi and if Group 1 does not match a whitespace, collect the match index, otherwise, match index + 1 value:

let searchTerm = "foo"
let string = "foo fooo,foo"

let regexp = new RegExp(`(^|\\s)${searchTerm}`, 'gi')
var matchIndices = [], m;
while(m = regexp.exec(string)) {
  if (m[1] === "") {
    matchIndices.push(m.index)
  } else {
    matchIndices.push(m.index+1)
  }
}

matchIndices.forEach(index => {
   console.log(index)
});