// 基本类型数据的复制
var a = 10;
var b = a; // b = 10
a = 20; // a = 20, b = 10
// 引用类型数据的复制
var m = [1, 2];
var n = m;
m[0] = 10;
console.log(n[0]); // 10

var src = [
 'alpha',
 ['bravo', 'chalie']
];
var dest = [];
for (var i = 0; i < src.length; i++) {
 dest[i] = src[i];
}
//此时，如果改变src中的引用字段，dest中相应的字段也会被改变
src[1].push('delta');
console.log(dest[1]); // ['bravo', 'chalie', 'delta']

 var src = ['alpha', 'bravo'],
  dest = [];
 dest = dest.concat(src);

 var a = ['alpha', 'bravo'],
  b = ['chalie', 'delta'],
  combine;
 combine = a.concat(b);

 var src = ['alpha', 'bravo'],
  dest = ['chalie', 'delta'];
 Array.prototype.push.apply(src, dest);

 var src = ['alpha', 'bravo'],
 var dest = src.slice(0);

 var src = {name: 'fox', age: 20},
  dest = null;
 dest = Object.assign({}, src);

function deep_copy(src, dest) {
 for (var p in src) {
  if (Array.isArray(src[p]) || src[p] instanceof Object) {
   dest[p] = Array.isArray(src[p]) ? [] : {};
   arguments.callee(dest[p], src[p]);
  }else {
   dest[p] = src[p];
  }
 }
}

 function deep_copy_in_json(src) {
  return JSON.parse(JSON.stringify(src));
 }