SOURCE

function test1 (array) {
    return array.concat().sort(() => {
        return Math.random() - 0.5
    })
}

function test2 (array) {
    array = array.concat()
    let rand = 0
    let tmp = null
    for(let i = 0; i < array.length; i++) {
        rand = i + Math.floor(Math.random() * (array.length - i));
        // [array[i], array[rand]] = [array[rand], array[i]]
        tmp = array[i]
        array[i] = array[rand]
        array[rand] = tmp
    }
    return array
}

let array = [1, 2, 3, 4, 5, 6, 7, 8, 9]
console.log(test2(array))