javascript错误处理

demo.js

'use strict'
var r1,r2,s=null;
try{
  r1=s.length; //产生错误
  r2=100;  //此语句不会执行
} catch(e){
  console.log('error'+e);
} finally{
  console.log('finally');
}

console.log(r1); //undefined
console.log(r2); //undefined