undefined
console.log(m);
dd is not defined:error
var m;
console.log(m); // undefined
var m = s;
console.log(m); // s error
var ---------->undefined;
var k = ----------->null;
出处:http://cnblogs.com/daishuguang
console.log(m);
dd is not defined:error
var m;
console.log(m); // undefined
var m = s;
console.log(m); // s error
var ---------->undefined;
var k = ----------->null;