正则

var str = "abcdefsafsf";
var subStr = "f";
var reg =  new RegExp(subStr,"gi");//等价于/f/gi
str = str.replace( reg, subStr+',');
console.log(reg);
console.log(str); //结果abcdef,saf,sf,

二、替换所有指定的字符

var str = "abcdefsafsf";
var repstr = "c";
console.log(replaceFun(str, repstr, "<span>" + repstr + "</span>"));
function replaceFun(str, repstr, newrepstr) {
  var reg =  new RegExp(repstr,"gi");
  return str.replace( reg, newrepstr);
}

三、转换成数组

var str = "fabcdefsafsffffs";
var subStr = "f";

console.log(regStrArr(str,subStr));
function regStrArr(str,subStr){
	var reg =  new RegExp(subStr,"gi");
	str = str.replace( reg, ','+subStr+',');
	var strArr = [];
	(str.split(",")).forEach(function(i,j){
		if(i!=""){
			strArr.push(i);
		}
	});
	console.log(strArr);
	return strArr;
}