JS implements the rock-paper-scissors game

/**
 * a is the content entered by the user * b is the random content of the computer */
var a = prompt('Please enter 1: Scissors 2: Rock 3: Paper');
var b = Math.random();
if (b < 0.3) {
    if (a == 1) {
        alert('The computer made the scissors, you made the scissors, it's a tie');
    } else if (a == 2) {
        alert('The computer played scissors, you played rock, you lose');
    } else {
        alert('The computer played scissors, you played cloth, you win');
    }
} else if (b < 0.6) {
    if (a == 1) {
        alert('The computer played rock, you played scissors, you lose');
    } else if (a == 2) {
        alert('The computer's stone and your stone are tied');
    } else {
        alert('The computer played rock, you played paper, you win');
    }
} else {
    if (a == 1) {
        alert('The computer played paper, you played scissors, you win');
    } else if (a == 2) {
        alert('The computer played paper, you played stone, you lost');
    } else {
        alert('The computer made the cloth, you made the cloth, it's a tie');
    }
}

var sum=0;//people's scorevar snm=0;//computer's scorefor(var i=0;i<3;i++){
    var a=prompt('Please enter 1, scissors 2, rock 3, cloth');
    var b=Math.random();
    if (b < 0.3) {
        if (a == 1) {
            alert('The computer made the scissors, you made the scissors, it's a tie');
        } else if (a == 2) {
            snm++;
            alert('The computer played scissors, you played rock, you lose');
        } else {
            sum++;
            alert('The computer played scissors, you played cloth, you win');
        }
    } else if (b < 0.6) {
        if (a == 1) {
            snm++;
            alert('The computer played rock, you played scissors, you lose');
        } else if (a == 2) {
            alert('The computer's stone and your stone are tied');
        } else {
            sum++;
            alert('The computer played rock, you played paper, you win');
        }
    } else {
        if (a == 1) {
            sum++;
            alert('The computer played paper, you played scissors, you win');
        } else if (a == 2) {
            snm++;
            alert('The computer played paper, you played stone, you lost');
        } else {
            alert('The computer made the cloth, you made the cloth, it's a tie');
        }
    }
}
alert('computer'+snm +'your score'+sum);