Here you can find the source of contains(pattern)
String.prototype.contains = function(pattern) { return this.indexOf(pattern) !== -1; };
String.prototype.contains = function(matcher) { const regex = new RegExp(matcher, 'i') return regex.test(this)
String.prototype.contains = function(needle) { return this.indexOf(needle) >= 0; };
String.prototype.contains = function (obj) { return this.indexOf(obj) >= 0; };
String.prototype.contains = function(pStr) { return this.indexOf(pStr) > -1; }; String.prototype.doUpperCase = function(pBeginIndex, pLength) { pLength = pLength || 1; return this.substring(pBeginIndex, pLength).toUpperCase() + this.substring(pBeginIndex + pLength); }; String.prototype.doLowerCase = function(pBeginIndex, pLength) { pLength = pLength || 1; ...
String.prototype.contains = function (palavra) { let indice = this.trim().indexOf(palavra); return indice >= 0;
String.prototype.contains = function(pattern) { return this.indexOf(pattern.canonize())>=0; };
String.prototype.contains = function(s) { return this.indexOf(s) >= 0; };
String.prototype.contains = function(s){ return this.indexOf(s) != -1; };
String.prototype.contains = function(s){ return (this.indexOf(s)!=-1);