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                合規國際互聯網加速 OSASE為企業客戶提供高速穩定SD-WAN國際加速解決方案。 廣告
                >[success] # var x = y = 100 發生什么 ~~~ 1.如果吧 var x = y = 100 拆開就會得到下面代碼 ~~~ ~~~ var x; // 變量提升聲明 x y = 100 // 隱式全局變量在特定情況下會出現泄漏 x = y // 變量賦值 console.log(x,y) 打印結果: 100 100 ~~~ * 通過之前學的推理驗證 ~~~ 1.通過之前概念通過'getOwnPropertyDescriptor'得到的'y' 的描述可以發現'configurable' 屬性為'true', 因此也可以推斷出'y'是一個隱式全局變量 2.x 和 y 是兩個不同的東西,前者是聲明的名字,后者是一個賦值過程可能創建的變量名。 3.let 和 const 同理但不會出現var 這種變量提升 ~~~ ~~~ var x = y = 100 console.log(Object.getOwnPropertyDescriptor(window,'y')) console.log(Object.getOwnPropertyDescriptor(window,'x')) console.log(x,y) 打印結果: {value: 100, writable: true, enumerable: true, configurable: true} {value: 100, writable: true, enumerable: true, configurable: false} 100 100 ~~~
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