javascript function

Question

function Foo(){
            getName = function(){
                console.log(1);
            };
           return this;
        }

        var getName = function (){ 
            console.log(4)
        };



          Foo().getName(); 

Why does the above code output 1;

After foo() is run, this is output. This is the window object. Does getName in foo() become a global function expression? And the following var getName is also a function expression; why is it printed? The result is 1;

foo, after execution, is it equivalent to the following code?

getName = function(){
            console.log(1);
        };

        var getName = function (){ 
            console.log(4)
        };



          getName(); //4

Answer 1

When Foo is not called

window.getName = function(){
    console.log(4);
}

When calling Foo()

getName = function(){
                console.log(1);
            };
// 相当于更改了 window.getName

After the call, return this in Foo does point to window, so the final result is 1.

Answer 2

function Foo(){
    getName = function(){
        console.log(1);
    };
    return this;
}
//全局声明一个变量getName
var getName = function (){ 
    console.log(4)
};
//重新赋值
getName = function () {
    console.log(1)
}
//最终打印结果为1
window.getName()

Answer 3

Foo().getName(); executes getName in Foo

Answer 4

function Foo(){
    getName = function(){
        console.log(1);
    };
    return this;
}

var getName = function (){ 
    console.log(4)
};

Foo().getName();

function Foo(){
    getName = function(){
        console.log(1);
    };
    return this;
}

var getName = function (){ 
    console.log(4)
};

getName = function () {
    console.log(1)
}

window.getName()

Answer 5

Check console.log(Foo()), are you sure it is window?

Answer 6

The getName in the Foo function is not declared with var, so it is global, so when Foo is run, the getName function inside the function will overwrite the one defined outside