js 本地存储并获取数据

1、本地存储

本地存储分为Cookie、 LocalStorage、SessionStorage

localStorage：

设置：localStorage.setItem(key, value)

读取：localStorage.getItem(key)

删除：localStorage.removeItem(key)

注意：设置或读取的值都是字符串，即便你存的值不是字符串，它也会帮你转成字符串(调toString())

// 存
localStorage.setItem('name', 'zs');
localStorage.setItem('age', 3);

// 取
console.log(localStorage.getItem('name'));
console.log(localStorage.getItem('age'));

// 删除
setTimeout(function () {
    localStorage.removeItem('age');
}, 4000);

var obj = {
    name: 'zs',
    age: 3
}

// console.log(obj.toString());
// localStorage.setItem('o', obj);

localStorage.setItem('o', JSON.stringify(obj))

console.log(JSON.parse(localStorage.getItem('o')));

2、JSON

JSON.parse(字符串); // 将长得像对象的字符串解析成对象

JSON.stringify(对象); // 将对象转成字符串

var obj = {
    name: 'zs',
    age: 3
}

var s = JSON.stringify(obj);
console.log(s); // {"name":"zs","age":3}
console.log(typeof s); // 'string'

var o = JSON.parse(s)
console.log(o); // {name: 'zs', age: 3}
console.log(typeof o); // 'object'