Javascript的参考价值
这个问题在这里已经有了答案：
我的理解是，这其实很简单：
所以，通过你的一些例子：
function f(a,b,c) {
// Argument a is re-assigned to a new value.
// The object or primitive referenced by the original a is unchanged.
a = 3;
// Calling b.push changes its properties - it adds
// a new property b[b.length] with the value "foo".
// So the object referenced by b has been changed.
b.push("foo");
// The "first" property of argument c has been changed.
// So the object referenced by c has been changed (unless c is a primitive)
c.first = false;
}
var x = 4;
var y = ["eeny", "miny", "mo"];
var z = {first: true};
f(x,y,z);
console.log(x, y, z.first); // 4, ["eeny", "miny", "mo", "foo"], false
例2：
var a = ["1", "2", {foo:"bar"}];
var b = a[1]; // b is now "2";
var c = a[2]; // c now references {foo:"bar"}
a[1] = "4"; // a is now ["1", "4", {foo:"bar"}]; b still has the value
// it had at the time of assignment
a[2] = "5"; // a is now ["1", "4", "5"]; c still has the value
// it had at the time of assignment, i.e. a reference to
// the object {foo:"bar"}
console.log(b, c.foo); // "2" "bar"
Javascript总是按价值传递。 但是，如果将对象传递给函数，则“值”实际上是对该对象的引用，因此该函数可以修改该对象的属性，但不会使该函数外部的变量指向某个其他对象。
一个例子：
function changeParam(x, y, z) {
x = 3;
y = "new string";
z["key2"] = "new";
z["key3"] = "newer";
z = {"new" : "object"};
}
var a = 1,
b = "something",
c = {"key1" : "whatever", "key2" : "original value"};
changeParam(a, b, c);
// at this point a is still 1
// b is still "something"
// c still points to the same object but its properties have been updated
// so it is now {"key1" : "whatever", "key2" : "new", "key3" : "newer"}
// c definitely doesn't point to the new object created as the last line
// of the function with z = ...
是的，Javascript总是按值传递，但是在数组或对象中，值是对它的引用，所以你可以“更改”内容。
但是，我想你已经阅读过它; 在这里你有你想要的文档：
http://snook.ca/archives/javascript/javascript_pass
链接地址: http://www.djcxy.com/p/469.html