javascript中var與let的區別
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
// let與var的區別
// 1.只在代碼塊中有效
for (var i = 0; i < 10; i++) {
}
console.log(i)//打印10
for (let i = 0; i < 10; i++) {
}
console.log(i)//報錯
//不能重復聲明
var a=1
var a=2
let b=1
let b=2 //報錯
//不存在變量提升
console.log(c)
var c="apple"
console.log(d)
let d="banana"
</script>
</body>
</html>
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