JS常用总结

let arr = [1,23,34,5,{a:1,b:2}];
// for of 打印内容值，遍历
for(let item of arr) {
    console.log(item); // 1,23,34
}
// for in 打印下标
for (let key in arr) {
    console.log(key); 
}
some 找到符合条件退出
foreach 直到循环结束哪怕有ruturn
map 直到循环结束哪怕有ruturn
every 全部相等才true，则false

const age = [1,2,6,334343,3434343,2];
const obj = { a:1, b:2}
console.log(Object.prototype.toString.call(age))  [object Array]
console.log(Object.prototype.toString.call(obj))  [object Object]