封装localstorage

const store = {
            storage: window.localStorage,

            set(key, val) {
                if (val === undefined) {
                    return this.remove(key)
                }
                this.storage.setItem(key, serialize(val))
                return val
            },

            get(key, def) {
                let val = deserialize(this.storage.getItem(key))
                return (val === undefined ? def : val)
            },

            has(key) {
                return this.get(key) !== undefined
            },

            remove(key) {
                this.storage.removeItem(key)
            },

            clear() {
                this.storage.clear()
            },

            getAll() {
                let ret = {}
                this.forEach((key, val) => {
                    ret[key] = val
                })
                return ret
            },

            forEach(callback) {
                for (let i = 0; i < this.storage.length; i++) {
                    let key = this.storage.key(i)
                    callback(key, this.get(key))
                }
            }
        }

        function serialize(val) {
            return JSON.stringify(val)
        }

        function deserialize(val) {
            if (typeof val !== 'string') {
                return undefined
            }
            try {
                return JSON.parse(val)
            } catch (e) {
                return val || undefined
            }
        }