js随机生成不重复的key

function closure() {
    const cache = {}
    return function getRandom() {
        let m = Math.random()
        while (cache[m]) {
            m = Math.random()
        }
        cache[m] = m
        return m
    }
}
const generateKey = closure()
// 生成
console.log(generateKey())
console.log(generateKey())
console.log(generateKey())
console.log(generateKey())