[TOC] ### 2.1console.log() ~~~ var a = 10; var b = 20; var c =a+b; console.log(a); console.log(b); console.log(c); ~~~ ### 2.2debugger调试 ~~~ /* 整个dom和相关关注加载完毕后，执行代码*/ window.onload = function(){ var a = 10; var b = 20; debugger; var c =a+b; } ~~~ ### 断点调试 ~~~ window.onload = function(){ var a = 10; var b = 20; var c =a+b; } ~~~