const run = initialize;run(1);run(1);run(1);function initialize(index) {    console.log('runs only once');    return function(index) {        console.log('useless code to use closure to make sure initialize only runs once');        return index;    }}這不起作用，但我不確定為什么，因為下面的代碼按預期工作，并且只在外部函數中運行一次代碼，同時多次運行內部函數。const getIndex = bigStuff();getIndex(500);getIndex(600);getIndex(700);function bigStuff(index) {    const myArray = new Array(300).fill('3');    console.log('created once');    return function(index) {        console.log('calling several times');        return myArray[index];    }}第二段代碼返回：created oncecalling several timescalling several times calling several times 雖然第一塊代碼返回：runs only onceruns only onceruns only once有人可以向我解釋 Javascript 引擎在后臺做什么嗎？因為我覺得當你使用閉包時，輸出會根據內部和外部函數內部的內容而有所不同。