JavaScript: String.prototype.lastIndexOf
By Xah Lee. Date: . Last updated: .
str.lastIndexOf(search_str)
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Return the start index of first occurrence of search_str, searching from right to left. Returns -1 if not found.
str.lastIndexOf(str, start_search_pos)
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Start search at start_search_pos.
const ss = "abcabc";
console.log( ss.lastIndexOf ( "b" ) );
console.log( ss.lastIndexOf ( "b", 1 ) );
console.log( ss.lastIndexOf ( "bc", 2 ) );
console.log( ss.lastIndexOf ( "bca", 1 ) );
console.log( ss.lastIndexOf ( "xy" ) );