JS calculates the probability of winning based on the prize weight

var prizes = ["First Prize","Second Prize","Third Prize","No Prize"]; //Award name array

var prizeWeight = [1, 5, 20, 74]; // Prize weight array, representing the percentage of the chance of winning each prize in the total. For example, the winning rate of the first prize is 1%, and the winning rate of the second prize is 5%.

//Set the award name, weight, etc. array var prizes = [
    {"name": "First Prize", "weight": 1}, 
    {"name": "Second Prize", "weight": 5}, 
    {"name": "Third Prize", "weight": 20}, 
    {"name": "Not Winning", "weight": 74}
];

//Array cumulative sum function: Array.reduce(function(prev ,cuurentValue), initialValue)
var weightSum = prizeWeight.reduce(function(prev, currVal){ //Calculate the sum of weights: 1+5+20+74=100
    return prev + currVal; //prev is the value after the previous accumulation, currVal is the value to be added this time}, 0);

//Lottery function var lottery = function(weightSum) {
    var res = "Not Winning"; //The default setting for the lottery result is "Not Winning"
    console.log("Award weight and value of this program:", weightSum);
    
    //Generate a random weight number between 0-weightSumvar random = Math.random()*weightSum; //Generate a random weight number (between 0 and weightSum)
    console.log("The random weight of this draw:", random);
    
    //Reorganize and sort the weight array var concatWeightArr = prizeWeight.concat(random); //Add random numbers to the weight array var sortedWeightArr = concatWeightArr.sort(function(a, b){return ab;}); //Sort the new weight array containing random numbers from small to large (ascending order) console.log("The new weight array containing random numbers is sorted in ascending order:", sortedWeightArr);
    
    //Array index of the weighted random number var randomIndex = sortedWeightArr.indexOf(random); //The position of the indexed random number in the new weight array randomIndex = Math.min(randomIndex, prizes.length -1); //The index of the weighted random number must not exceed the length of the prize array - 1, recalculate the index position of the random number in the prize array console.log("Array index corresponding to this weighted random number:", randomIndex);
    
    //Get the corresponding prize res = prizes[randomIndex]; //Get the result of this lottery from the prize array console.log("The result of this lottery:", res);
    
    return {"weightSum": weightSum , "weightRandom": random, prizeIndex: randomIndex, "data": res}; //Return the result of this lottery};

//layui modular reference layui.use(['jquery', 'util'], function(){
    var $ = layui.$, util = layui.util;
    
    //Set arrays for prize name, weight, number of wins, etc. var prizes = ["First Prize", "Second Prize", "Third Prize", "No Winner"]; //Award name array var prizeWeight = [1, 5, 20, 74]; //Prize weight array, representing the percentage of the chance of winning each prize in the total. For example, the winning rate of the first prize is 1%, and the winning rate of the second prize is 5%.            
    
    // Developers can also declare award names, weights, and other arrays in one object // var prizes = [
    // {"name": "First Prize", "weight": 1}, 
    // {"name": "Second Prize", "weight": 5}, 
    // {"name": "Third Prize", "weight": 20}, 
    // {"name": "Not winning", "weight": 74}
    //];                
    
    //Array cumulative sum function: Array.reduce(function(prev ,cuurentValue), initialValue)
    var weightSum = prizeWeight.reduce(function(prev, currVal){ //Calculate the sum of weights: 1+5+20+74=100
        return prev + currVal; //prev is the value after the previous accumulation, currVal is the value to be added this time}, 0);
    document.getElementById("weightSum").innerhtml = weightSum; //Set weight and value //Lottery function var lottery = function(weightSum) {
        var res = "Not Winning"; //The default setting for the lottery result is "Not Winning"
        console.log("Award weight and value of this program:", weightSum);
        
        //Generate a random weight number between 0-weightSumvar random = Math.random()*weightSum; //Generate a random weight number (between 0 and weightSum)
        console.log("The random weight of this draw:", random);
        
        //Reorganize and sort the weight array var concatWeightArr = prizeWeight.concat(random); //Add random numbers to the weight array var sortedWeightArr = concatWeightArr.sort(function(a, b){return ab;}); //Sort the new weight array containing random numbers from small to large (ascending order) console.log("The new weight array containing random numbers is sorted in ascending order:", sortedWeightArr);
        
        //Array index of the weighted random number var randomIndex = sortedWeightArr.indexOf(random); //The position of the indexed random number in the new weight array randomIndex = Math.min(randomIndex, prizes.length -1); //The index of the weighted random number must not exceed the length of the prize array - 1, recalculate the index position of the random number in the prize array console.log("Array index corresponding to this weighted random number:", randomIndex);
        
        //Get the corresponding prize res = prizes[randomIndex]; //Get the result of this lottery from the prize array console.log("The result of this lottery:", res);
        
        return {"weightSum": weightSum , "weightRandom": random, prizeIndex: randomIndex, "data": res}; //Return the result of this lottery};

    //Register button event $('.layui-btn[data-type="save"]').on('click', function () {
        var res = lottery(weightSum);
        document.getElementById("dateNow").innerhtml = util.toDateString(new Date()); //Output the time of this lottery document.getElementById("weightRandom").innerHTML = res.weightRandom; //Output the weighted random number of this lottery document.getElementById("printData").innerHTML = res.data; //Output the result of this lottery //Reset the font color of the winning rules text $('.rule-body>p').css("color", "inherit");
        $('.rule-body>p:eq(' + res.prizeIndex + ')').css("color", "red");
    });
});