lovecoding
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VIP24


			
				
					
						
						
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  <script>
    /* 
    变量提升
    通过var 定义的变量  会在当前的作用域最上方  定义这个变量  没有值 undefined
    */
    // console.log(a)
    // var a = 10

    /* console.log(a)
    let a = 10  报错*/

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