如何使用Javascript从JSON文件中选择随机对象？

Question

In my Discord Bot that I am making, it needs to select a random object from a JSON file. My current code is this:

  function spawn(){ if (randomNum === 24) return const name = names.randomNum const embed = new Discord.RichEmbed() .setTitle(`${name} has been found!`) .setColor(0x00AE86) .setThumbnail(`attachment://./sprites/${randomNum}.png`) .setTimestamp() .addField("Quick! Capture it with `>capture`!") msg.channel.send({embed}); } 

The JSON file looks like this:

 { "311": "Blargon", "310": "Xryzoz", "303": "Noot", "279": "", "312": "Arragn", "35": "Qeud", ... } 

I want it to pick a random one of those, such as 303 , and post it in a rich embed. What do I do from here?

Answer 1

 const jsonData = { "311": "Blargon", "310": "Xryzoz", "303": "Noot", "279": "", "312": "Arragn", "35": "Qeud", } const values = Object.values(jsonData) const randomValue = values[parseInt(Math.random() * values.length)] console.log(randomValue) 

Answer 2

You can select a random name like this:

// Create array of object keys, ["311", "310", ...]
const keys = Object.keys(names)

// Generate random index based on number of keys
const randIndex = Math.floor(Math.random() * keys.length)

// Select a key from the array of keys using the random index
const randKey = keys[randIndex]

// Use the key to get the corresponding name from the "names" object
const name = names[randKey]

// ...

Answer 3

This can be done in two steps

Loading Json file using Javascript and local server

1> Create a Json file, name it botNames.json , add your data.

Note: .json files can only contain Json Object, Array or Json literal

{
    "311": "Blargon",
    "310": "Xryzoz",
    "303": "Noot",
    "279": "",
    "312": "Arragn",
    "35": "Qeud"
}

Use XMLHttpRequest() to load the data, you can use below function to load the .json file passing a callback function and the path as an argument.

function loadJSON(callback,url) {   
  var xobj = new XMLHttpRequest();
  xobj.overrideMimeType("application/json");
  xobj.open('GET', url, true); 
  xobj.onreadystatechange = function () {
        if (xobj.readyState == 4 && xobj.status == "200") {
          callback(xobj.responseText);
        }
  };
  xobj.send(null);
}

To generate a random index you can use the below expression

Math.floor(lowerLimt + (upperLimit - lowerLimit+1)*Math.Random())

this will give you values in the range [lowerLimit,upperLimit)

Note: This is possible because Math.random() generates a fractional number in the range [0,1)

Your callback function will be

function callback1(response){
        var botNames = JSON.parse(response)
        var keys = Object.keys(botNames);
        var randomProperty = keys[Math.floor(keys.length*Math.random())]
        var botName = botNames[randomProperty]
        console.log(botName);
    }

You can use above concepts in your code as

 function loadJSON(callback,url) { var xobj = new XMLHttpRequest(); xobj.overrideMimeType("application/json"); xobj.open('GET', url, true); xobj.onreadystatechange = function () { if (xobj.readyState == 4 && xobj.status == "200") { // sending the resonse to your callback callback(xobj.responseText); } }; xobj.send(null); } function spawn(){ loadJSON(function(response){ //This is your callback function var names = JSON.parse(response) var keys = Object.keys(botNames); var randomNum = keys[Math.floor(keys.length*Math.random())] if (randomNum === 24) return const name = names[randomNum] const embed = new Discord.RichEmbed() .setTitle(`${name} has been found!`) .setColor(0x00AE86) .setThumbnail(`attachment://./sprites/${randomNum}.png`) .setTimestamp() .addField("Quick! Capture it with `>capture`!") msg.channel.send({embed}); },'/PATH_TO_YOUR_JSON/botNames.json') }