/outcomes-recipes

Primary LanguageJavaScript

Re-implement string.indexOf()

This was created during my time as a Code Chrysalis Student

Write a function called stringIndexOf that takes in two strings. If the first string contains the second string as a contiguous substring, return the index where it occurs.

If the string cannot be found, return -1.

If the string occurs multiple times, return the location of the first occurence.

Since this is a logic exercise, you may NOT use the following built-in methods as part of your implementation:

  • string.indexOf()
  • string.substr()
  • string.substring()
  • regular expressions

Examples:

  • stringIndexOf("abc", "ab") --> 0
  • stringIndexOf("abc", "bc") --> 1
  • stringIndexOf("abc", "") --> 0
  • stringIndexOf("", "abc") --> -1
  • stringIndexOf("abc", "abcd") --> -1

All strings are valid input.

If an input is invalid, throw an Error.