let 局部變量聲明
var arr = [1,2,3];
for(let i of arr){
console.log(i); //1,2,3
}
const 常量聲明
特征 聲明后不能修改 否則報(bào)錯
const i = 2;
i = 3; // 報(bào)錯 Uncaught TypeError: Assignment to constant variable.
var arr = [1,2,3];
for(let i of arr){
console.log(i); //1,2,3
}
const i = 2;
i = 3; // 報(bào)錯 Uncaught TypeError: Assignment to constant variable.