编码解码 encodeURIComponent与decodeURIComponent （base64编码解码）btoa与atob

var test1="http://www.w3school.com.cn/My first/"

document.write(encodeURIComponent(test1)+ "<br />")
document.write(decodeURIComponent(test1))

var str = "RUNOOB";
var enc = window.btoa(str);
var dec = window.atob(enc);