js-值传递和引用传递实例代码

<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<script>
//按值传递(call by value)
var x=1;
function test(o){
	o=2;
	}
test(x);
console.log(x);

//按引用传递(call by reference)
var obj = {x : 1};
function test(o){
	o.x=2;
	}
test(obj);
console.log(obj.x);

//按共享传递(call by sharing)
var obj = {x : 1};
function test(o) {
	o.x=2;
    o = 100;
	t = 200;
	console.log(o);
	return o;
}
var s=test(obj);
console.log("s:"+s);
console.log("t:"+t);
console.log("obj.x:"+obj.x); // 仍然是1, obj并未被修改为100
console.log("o:"+o);

//例子1
function setName(obj) {
	obj.name = 'aaa';
	var obj = new Object(); // 如果是按引用传递的,此处传参进来obj应该被重新引用新的内存单元
	obj.name = 'ccc';
	return obj;
}
var person = new Object();
person.name = 'bbb';
var newPerson = setName(person);
console.log(person.name + ' | ' + newPerson.name); // aaa | ccc

//例子2
var a = {num:'1'};
var b = {num:'2'};
function change(obj){
	obj.num = '3';
	obj = b;
	return obj.num;
}
var result = change(a);
console.log(result + ' | ' + a.num); // 2 | 3 

//例子3  原始类型是不可变的，只有对象是可变的
var str = "abc";
console.log(str[0]);
str[0] = "d";
console.log(str[0]);
console.log(str);

//例子4	对象的值是引用的，可变的
var obj = {x : 1};
obj.x = 100;
var o = obj;
o.x = 1;
console.log("obj.x:"+obj.x); // 1, 被修改
o = true;
console.log("obj.x:"+obj.x); // 1, 不会因o = true改变
</script>


</body>
</html>
js-值传递和引用传递实例代码

js-值传递和引用传递实例代码

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