javascript中浅拷贝和深拷贝的理解
什么是拷贝？
简单地说就是复制，对数据的复制
浅拷贝：改变拷贝者的值，被拷贝者的值也会变化
深拷贝：改变拷贝者的值，被拷贝者的值不会变化
由于基本数据类型是存放在栈中，拷贝的就是自己本身，所以就是深拷贝
1：number
var a = 1;
b = a;
console.log(a);//1
console.log(b);//1
b = 2;
console.log(a);//1
console.log(b);//22:string
var a = "hello";
b = a;
console.log(a);//hello
console.log(b);//hello
b = "world";
console.log(a);//hello
console.log(b);//world3:boolean
var a = true;
b = a;
console.log(a);//true
console.log(b);//true
b = false;
console.log(a);//true
console.log(b);//false4:null
var a = null;
b = a;
console.log(a);//null
console.log(b);//null
b = "hello";
console.log(a);//null
console.log(b);//hello5:undefined
var a = undefined;
b = a;
console.log(a);//undefined
console.log(b);//undefined
b = "hello";
console.log(a);//undefined
console.log(b);//hello对于引用数据类型，通过复制的形式一般就是浅拷贝
6：Array浅拷贝
复制的只是引用，a和b在栈中是不同的值，但二者在堆中是同一块区域
var a = [1,2,3];
b = a;
console.log(a);//[1,2,3]
console.log(b);//[1,2,3]
b[1] = 4;
console.log(a);//[1,4,3]
console.log(b);//[1,4,3]7：Array深拷贝
复制的不仅是引用，还有引用值，堆中也未b开辟了一块空间
8：Array深拷贝slice(0)
var a = [1,2,3];
b = a.slice(0);
console.log(a);//[1,2,3]
console.log(b);//[1,2,3]
b[1] = 4;
console.log(a);//[1,2,3]
console.log(b);//[1,4,3]9：Array深拷贝concat()
var a = [1,2,3];
b = a.concat();
console.log(a);//[1,2,3]
console.log(b);//[1,2,3]
b[1] = 4;
console.log(a);//[1,2,3]
console.log(b);//[1,4,3]10：Array深拷贝deepCopy()
var a = [1,2,3];
b = [];
deepCopy(a,b)
console.log(a);//[1,2,3]
console.log(b);//[1,2,3]
b[1] = 4;
console.log(a);//[1,2,3]
console.log(b);//[1,4,3]function deepCopy(arr1,arr2){for(var i = 0,L = arr1.length;i<L;i++){arr2[i] = arr1[i]}
}11：上面三种方法只针对一位数组，对于多维数组有局限性
12：Array多维数组深拷贝deepCopy()
var a = [[1,2,3,4],5,6];
b = [];
deepCopy(a,b)
console.log(a);//[ [ 1, 2, 3, 4 ], 5, 6 ]
console.log(b);//[ [ 1, 2, 3, 4 ], 5, 6 ]
b[0][1] = 7;
b[1] = 8;
console.log(a);//[ [ 1, 7, 3, 4 ], 5, 6 ]
console.log(b);//[ [ 1, 7, 3, 4 ], 8, 6 ]function deepCopy(arr1,arr2){for(var i = 0,L = arr1.length;i<L;i++){arr2[i] = arr1[i]}
}13：Array多维数组深拷贝slice(0)
var a = [[1,2,3,4],5,6];
b = a.slice(0)
console.log(a);//[ [ 1, 2, 3, 4 ], 5, 6 ]
console.log(b);//[ [ 1, 2, 3, 4 ], 5, 6 ]
b[0][1] = 7;
b[1] = 8;
console.log(a);//[ [ 1, 7, 3, 4 ], 5, 6 ]
console.log(b);//[ [ 1, 7, 3, 4 ], 8, 6 ]14：Array多维数组深拷贝concat()
var a = [[1,2,3,4],5,6];
b = a.concat()
console.log(a);//[ [ 1, 2, 3, 4 ], 5, 6 ]
console.log(b);//[ [ 1, 2, 3, 4 ], 5, 6 ]
b[0][1] = 7;
b[1] = 8;
console.log(a);//[ [ 1, 7, 3, 4 ], 5, 6 ]
console.log(b);//[ [ 1, 7, 3, 4 ], 8, 6 ]15：Array多维数组深拷贝deepCopy()优化处理
var a = [[1,2,3,[7,8]],5,6];
b = [];
deepCopy(a,b)
console.log(a);//[ [ 1, 2, 3, [ 7, 8 ] ], 5, 6 ]
console.log(b);//[ [ 1, 2, 3, [ 7, 8 ] ], 5, 6 ]
b[0][1] = 7;
b[0][3][1] = 9;
b[1] = 8;
console.log(a);//[ [ 1, 2, 3, [ 7, 8 ] ], 5, 6 ]
console.log(b);//[ [ 1, 7, 3, [ 7, 9 ] ], 8, 6 ]function deepCopy(arr1,arr2){var tempArr = [];for(var i = 0,L = arr1.length;i<L;i++){if(arr1[i] instanceof Array){deepCopy(arr1[i],tempArr);arr2[i] = tempArr}else {arr2[i] = arr1[i];}}
}16:对象浅拷贝
var a = {name:"zyb",age:23};
var b = a;
console.log(a)//{ name: 'zyb', age: 23 }
console.log(b);//{ name: 'zyb', age: 23 }a.name = "lisi";
console.log(a)//{ name: 'lisi', age: 23 }
console.log(b);//{ name: 'lisi', age: 23 }17：对象深拷贝
var a = {name:"zyb",age:23};
var b = new Object();b.name = a.name;
b.age = a.age;
console.log(a)//{ name: 'zyb', age: 23 }
console.log(b);//{ name: 'zyb', age: 23 }a.name = "lisi";
console.log(a)//{ name: 'lisi', age: 23 }
console.log(b);//{ name: 'zyb', age: 23 }18：对象深拷贝：内嵌对象
var a = {name:"zyb",age:23,list:{goods:"篮球",detail:"运动是好的"
}};
var b = new Object();b.name = a.name;
b.age = a.age;
b.list = a.list;
console.log(a)//{ name: 'zyb', age: 23, list: { goods: '篮球', detail: '运动是好的' } }
console.log(b);//{ name: 'zyb', age: 23, list: { goods: '篮球', detail: '运动是好的' } }a.name = "lisi";
a.list.goods = "足球";
console.log(a)//{ name: 'lisi', age: 23, list: { goods: '足球', detail: '运动是好的' } }
console.log(b);//{ name: 'zyb', age: 23, list: { goods: '足球', detail: '运动是好的' } }19：对象深拷贝deepCopy()
var a = {name:"zyb",age:23};
var b = deepCopy(a);console.log(a)//{ name: 'zyb', age: 23 }
console.log(b);//{ name: 'zyb', age: 23 }a.name = "lisi";console.log(a)//{ name: 'lisi', age: 23 }
console.log(b);//{ name: 'zyb', age: 23 }function deepCopy(obj){var result = {};for(var key in obj){if(obj.hasOwnProperty(key)){result[key] = typeof obj[key] === 'object' ? deepCopy(obj[key]) : obj[key];}}return result;
}20：对象深拷贝deepCopy()：内嵌对象
var a = {name:"zyb",age:23,list:{goods:"篮球",detail:"运动是好的"
}};
var b = deepCopy(a)console.log(a)//{ name: 'zyb', age: 23, list: { goods: '篮球', detail: '运动是好的' } }
console.log(b);//{ name: 'zyb', age: 23, list: { goods: '篮球', detail: '运动是好的' } }a.name = "lisi";
a.list.goods = "足球";
console.log(a)//{ name: 'lisi', age: 23, list: { goods: '足球', detail: '运动是好的' } }
console.log(b);//{ name: 'zyb', age: 23, list: { goods: '篮球', detail: '运动是好的' } }function deepCopy(obj){var result = {};for(var key in obj){if(obj.hasOwnProperty(key)){result[key] = typeof obj[key] === 'object' ? deepCopy(obj[key]) : obj[key];}}return result;
}21:jquery中对数组的拷贝
var a = [1,2,3];
var b = $.extend([],a);
console.log(a)//[1,2,3]
console.log(b)//[1,2,3]
b.push(4)
console.log(a)//[1,2,3]
console.log(b)//[1,2,3,4]22:jquery中对对象的拷贝1
var a = {a1:1,a2:2,a3:3};
var b = $.extend({},a);
console.log(a)//{a1:1,a2:2,a3:3}
console.log(b)//{a1:1,a2:2,a3:3}
b.b4 = 4
console.log(a)//{a1:1,a2:2,a3:3}
console.log(b)//{a1:1,a2:2,a3:3,b4:4}23:jquery中对对象的拷贝2
var a = {a1:1,a2:2,a3:3};
var b = $.extend({b0:0},a);
console.log(a)//{a1:1,a2:2,a3:3}
console.log(b)//{b0:0,a1:1,a2:2,a3:3}
b.b4 = 4
console.log(a)//{a1:1,a2:2,a3:3}
console.log(b)//{b0:0,a1:1,a2:2,a3:3,b4:4}24:jquery中对对象的拷贝3
var a = {a1:1,a2:2,a3:3};
var c = {c1:1,c2:2,c3:3};
var b = $.extend({b0:0},a,c);
console.log(a)//{a1:1,a2:2,a3:3}
console.log(b)//{a1:1,a2:2,a3:3,b0:0,c1:1,c2:2,c3:3}
b.b4 = 4
console.log(a)//{a1:1,a2:2,a3:3}
console.log(b)//{a1:1,a2:2,a3:3,b0:0.b4:4,c1:1,c2:2,c3:3}
函数和input()函数用法解析)
是什么意思)
