Isomorphic Strings

Problem statement

Given two strings s and t, determine if they are isomorphic.

Two strings s and t are isomorphic if the characters in s can be replaced to get t.

All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character, but a character may map to itself.

Example 1:

Input: s = "egg", t = "add"Output: true

Example 2:

Input: s = "foo", t = "bar"Output: false

Example 3:

Input: s = "paper", t = "title"Output: true

Constraints:

• 1 <= s.length <= 5 * 104
• t.length == s.length
• s and t consist of any valid ascii character.

My solution

/**
 * @param {string} s
 * @param {string} t
 * @return {boolean}
 */
var isIsomorphic = function(s, t) {
    if (s === t) {
        return true;
    }
    
    const len = s.length;
    let i = 0;
    if (len !== t.length) {
        return false;
    }
    
    while (i < len) {
        if (s.indexOf(s.charAt(i)) === t.indexOf(t.charAt(i))) {
            i++
        } else {
            break;
        }
    }
    
    return i === len
};