foriterate 迭代器一個接著一個的意思for...loop#for (let X = 0; x < array.length; x++) { const a = array[x];}Copyfor...in#取得陣列或是物件裡的 keyconst foo = ['a','b','c'] const bar = { a:1, b:2,} for (const key in foo ){ console.log(key)} # 0,1,2 for (const key in bar ){ console.log(key)} #a,b Copyfor...of#取得陣列裡的 value物件沒有順序性 必須先把 values 取出來for (const iterate of foo) { console.log(iterate);} for (const value of bar) { console.log(value);} for (const value of Object.values(bar)) { console.log(value);}Copy