JavaScript是按引用传递还是按值传递的?
以下是来自JavaScript: The Good Parts的一个例子。我对rectangle
函数中的my
参数感到非常困惑。它实际上是undefined
,并在函数内部被重新定义。没有原始引用。如果我从函数参数中删除它,则无法访问内部区域函数。
这是闭包吗?但没有返回函数。
var shape = function (config) {
var that = {};
that.name = config.name || "";
that.area = function () {
return 0;
};
return that;
};
var rectangle = function (config, my) {
my = my || {};
my.l = config.length || 1;
my.w = config.width || 1;
var that = shape(config);
that.area = function () {
return my.l * my.w;
};
return that;
};
myShape = shape({
name: "Unhnown"
});
myRec = rectangle({
name: "Rectangle",
length: 4,
width: 6
});
console.log(myShape.name + " area is " + myShape.area() + " " + myRec.name + " area is " + myRec.area());