String substr()The substr() method of strings returns part of a string, starting from an index and ending a given number of characters after.limitedhttps://tc39.es/ecma262/multipage/additional-ecmascript-features-for-web-browsers.html#sec-string.prototype.substrhttps://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String/substrjavascript.builtins.String.substrhttps://nowyoucanuse.com/features--string-substr.html