JavaScript: 作用域与作用域链, scope & scope chain about blog

[xvno]

this

注意避免 let/const 污染 高尚 的JS

name = 'window.name'
o = {
    name: 'o.name',
    getName(){
        console.log(name, this.name);
    }
}

function foo() {
	var name = 'foo.name';
	return {
    	name: 'oo.name',
	getName(){
            var name = 'getName.name';
            console.log(name, this.name);
            return function() {
                console.log(name, this.name);
            }
	}
    }
}
o.getName();             // window.name o.name ----------------fn-2
oo = foo();				 
ooo = oo.getName();      // getName.name oo.name --------------fn-2
ooo();                   // getName.name window.name ----------fn-2
bar = oo.getName;  
oooo = bar();            // getName.name window.name ----------fn-2
oooo();                  // getName.name window.name ----------fn-2

name = 'window.name'
o = {
    name: 'o.name',
    getName(){
        console.log(name, this.name);
    }
}

function foo() {
	var name = 'foo.name';
	return {
    	name: 'oo.name',
        getName(){
            console.log(name, this.name);
            var name = 'getName.name';
            return function() {
                console.log(name, this.name);
            }
        }
    }
}
o.getName();             // window.name o.name ----------------fn-2
oo = foo();				 
ooo = oo.getName();      // undefined oo.name --------------fn-2
ooo();                   // getName.name window.name ----------fn-2
bar = oo.getName;  
oooo = bar();            // undefined window.name ----------fn-2
oooo();                  // getName.name window.name ----------fn-2