js 生成指定位随机数

function createRandom(len = 32) {
    const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    let str = ''
    for (let i = 0; i < len; i++) {
        str += chars.charAt(Math.floor(Math.random() * chars.length))
    }
    return str;
}