ES6學習筆記1

let命令 1.不存在變量提高 console.log(foo); //undefined var foo = 2; console.log(bar); //Uncaught ReferenceError: bar is not defined let bar = 2; 2.不容許重複聲明 let a = 10; var a = 20; //Uncaught SyntaxError: Ident

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