How can I found the index of a array of characters in a string without looping on the array characters

Question

i'm searching a simple way to find the index of one character / string between a list of characters.

Something which looks like

"3.14".indexOf([".",","])
"3,14".indexOf([".",","])

Both should return 1.

Answer 1

One way:

const testRegex = /\.|,/
const match = testRegex.exec("3.14");
console.log(match && match.index)

It uses a regular expression to search for either character, and uses the exec method on regular expressions which returns an object that has the index of the start of the match.

Answer 2

You can loop through the array and return the first character's index whose index is not -1:

function getIndex(str, array){
  for(e of array){
    let index = str.indexOf(e);
    if(index != -1){
      return index;
    }
  }
}

console.log(getIndex("3.14", [".",","]))
console.log(getIndex("3,14", [".",","]))

You can also use Array.reduce:

function getIndex(str, array){
  return array.reduce((a,b) => a == -1 ? a = str.indexOf(b) : a, -1)
}

console.log(getIndex("3.14", [".",","]))
console.log(getIndex("3,14", [".",","]))