[Javascript] prototype replaceAll

자바스크립트로 replaceAll 구현하기: 프로토타입 사용 String.prototype.replaceAll = function(targetStr,replaceStr){    thisStr = this.toString();    var idx = thisStr.indexOf( targetStr );    while ( idx > -1 ) {        thisStr = thisStr.replace( targetStr, replaceStr );        idx = thisStr.indexOf( targetStr );    }    return thisStr; }