| 'use strict'; |
| |
| var GetIntrinsic = require('get-intrinsic'); |
| var callBound = require('call-bind/callBound'); |
| |
| var $TypeError = GetIntrinsic('%TypeError%'); |
| |
| var IsIntegralNumber = require('./IsIntegralNumber'); |
| var Type = require('./Type'); |
| |
| var $slice = callBound('String.prototype.slice'); |
| |
| // https://ecma-international.org/ecma-262/12.0/#sec-stringindexof |
| |
| module.exports = function StringIndexOf(string, searchValue, fromIndex) { |
| if (Type(string) !== 'String') { |
| throw new $TypeError('Assertion failed: `string` must be a String'); |
| } |
| if (Type(searchValue) !== 'String') { |
| throw new $TypeError('Assertion failed: `searchValue` must be a String'); |
| } |
| if (!IsIntegralNumber(fromIndex) || fromIndex < 0) { |
| throw new $TypeError('Assertion failed: `fromIndex` must be a non-negative integer'); |
| } |
| |
| var len = string.length; |
| if (searchValue === '' && fromIndex <= len) { |
| return fromIndex; |
| } |
| |
| var searchLen = searchValue.length; |
| for (var i = fromIndex; i <= (len - searchLen); i += 1) { |
| var candidate = $slice(string, i, i + searchLen); |
| if (candidate === searchValue) { |
| return i; |
| } |
| } |
| return -1; |
| }; |