StringLastIndexOf.jsā¢1.1 kB
'use strict';
var $TypeError = require('es-errors/type');
var substring = require('./substring');
var isInteger = require('../helpers/isInteger');
// https://262.ecma-international.org/16.0/#sec-stringlastindexof
module.exports = function StringLastIndexOf(string, searchValue, fromIndex) {
if (typeof string !== 'string') {
throw new $TypeError('Assertion failed: `string` must be a string');
}
if (typeof searchValue !== 'string') {
throw new $TypeError('Assertion failed: `searchValue` must be a string');
}
if (!isInteger(fromIndex) || fromIndex < 0) {
throw new $TypeError('Assertion failed: `fromIndex` must be a non-negative integer');
}
var len = string.length; // step 1
var searchLen = searchValue.length; // step 2
if (!((fromIndex + searchLen) <= len)) {
throw new $TypeError('Assertion failed: fromIndex + searchLen ā¤ len'); // step 3
}
for (var i = fromIndex; i >= 0; i--) { // step 4
var candidate = substring(string, i, i + searchLen); // step 4.a
if (candidate === searchValue) {
return i; // step 4.b
}
}
return 'NOT-FOUND'; // step 5
};