I am very new to JavaScript and I'm sure this question has been answered quite a bit, but when I search my question I don't seem to find an answer (or one that I actually understand :D)
Currently, I'm trying to create a tool to help kids with there multiplication facts and I'm having trouble getting the program to generate new random numbers.
var r1 = Math.floor(Math.random() * 13);
var r2 = Math.floor(Math.random() * 13);
function start() {
println("Welcome to the multipilcation helper! ");
var num = readLine("Pick a number you want to practice or type 'random'!");
var ques = readLine("How many questions do you want?");
if (num == "random") {
for (var i = 0; i < ques; i++) {
var answer = r1 * r2;
println(r1 + "*" + r2);
var check = readLine("what is the answer");
if (check == answer) {
println("thats correct!");
} else {
println("thats wrong! ");
}
}
}
}
The problem is that my variables seem to pick a random number as soon as the script starts and stick with it instead of giving me a new random number.
Can anyone help me out and tell me how to get a new random number every time the variable is called?
Simply create yourself a method like the one below and use it like r() to get a new random number every call.
function r() {
return Math.floor(Math.random() * 13);
}
console.log(r());
console.log(r());
console.log(r());
In your loop you should be reassigning the random numbers so that they are reassigned every iteration of the loop. Otherwise they stay static to the value you give them at the top.
Also, you should use triple equals in Javascript when checking for equality as it is best practice.
function start() {
console.log("Welcome to the multipilcation helper! ");
var num = prompt("Pick a number you want to practice or type 'random'!");
var ques = prompt("How many questions do you want?");
if (num == "random") {
for (var i = 0; i < ques; i++) {
var r1 = Math.floor(Math.random() * 13);
var r2 = Math.floor(Math.random() * 13);
var answer = r1 * r2;
console.log(r1 + "*" + r2);
var check = prompt("what is the answer");
if (check == answer) {
console.log("thats correct!");
} else {
console.log("thats wrong! ");
}
}
}
}
start()
You random numbers are being static at the moment. They need to be called again. Move your r1 and r2 assignments inside the for.
I don't have enough reputation to comment, but will update the answer
if you explain it with more details.
You need to put the random call in a function in order for it to create a new number each time. When you assign it directly to a variable as you have, it only runs once and stores that value in the variable.
// pick a number between 0 and 13
var random = function() {
return Math.floor(Math.random() * 13);
}
function start(){
for(var i = 0; i < 15; i++){
// call random function for each number and store in a var
var number1 = random();
var number2 = random();
var answer = number1 * number2;
console.log('equation:', number1 + '*' + number2);
console.log('answer:', answer);
}
}
// call the start function
start()
Related
I have an array of bills and an empty array for tips.
I'm trying to call a tipcalculator function within a for loop so I can calculate the tips of each one of the bills in the bills array, store that result in the empty tips array. Is this possible to be done?
Thanks
var bills = [123,145,12,44];
var tips = [];
function calculateTips(bill){
let tip;
if(bill<10){
tip = .2;
}
if(bill>=10 && bill <20){
tip = .10;
} else {
tip = 0.1;
}
return tip * bill;
for(var i=0; i<bills.length; i++){
var temp = calculateTips(bills[i]);
tips.push(temp);
}
};
Your loop needs to be outside of the function. As the documentation says:
The return statement ends function execution and specifies a value to
be returned to the function caller.
var bills = [123,145,12,44];
var tips = [];
function calculateTips(bill){
let tip;
// Since the bill will only fall into one of your tests
// use else if, rather than an if followed by another if
if(bill < 10){
tip = .2;
} else if(bill >= 10 && bill < 20){
tip = .10;
} else {
tip = 0.1;
}
// once a function reaches a return statement
// it will return the specified value (if any)
// and then stop processing the function.
return tip * bill;
}
for(var i=0; i<bills.length; i++){
var temp = calculateTips(bills[i]);
tips.push(temp);
}
console.log(tips);
There is no difference between tip=.10 and tip=0.1. And you can shorten your script considerably, see below.
const calculateTips=bill=>((bill>=10?.1:.2)*bill).toFixed(2);
var bills = [123,145,12,44,8];
let tips=bills.map(calculateTips);
console.log(tips);
Fun fact: Your formula leads to higher tips for 8$ than for 12$ bills.
I'm creating a game, and once the two scores match I want it to show "You won" but I can't get the two scores to compare.
I tried the parseInt method and .val method, no go.
var numberFour = Math.floor(Math.random() * 3 + 10);
$("#four").on("click", function() {
playerScore = playerScore + numberFour
$("#score").text(playerScore);
})
console.log(numberFour);
for (var i = 0; i < 121; i++) {
var goalNumber = Math.floor(Math.random() * 100 + 9);
$("#goal").text(goalNumber);
};
if (playerScore == goalNumber) {
console.log("You won!");
}
else {
console.log("You suck!")
}
I'm not sure why you're running through such a large loop for goalNumber, but try this code out. I changed your loop so you're not re-declaring goalNumber 120+ times and put your comparison inside your onclick call so it's continuously called every time you update your playerScore. I don't know how you've got your game setup, but I think it'll be tough for them to ever be equal when you're using random numbers.
Also, it helps to know when you're calling portions of your code. Omitting event handlers makes it difficult to debug your code. How else do we know when things are being used?
var playerScore = 0;
var goalNumber = 0;
var numberFour = Math.floor(Math.random() * 3 + 10);
for (var i = 0; i < 121; i++) {
goalNumber = Math.floor(Math.random() * 100 + 9);
$("#goal").text(goalNumber);
};
$("#four").on("click", function() {
playerScore += numberFour;
$("#score").text(playerScore);
if (playerScore == goalNumber) {
console.log("You won!");
}
else {
console.log("You suck!")
}
});
So, first and foremost, it's important to note that I'm adding a feature to something I didn't design. I'm really new to JavaScript, and I'm trying to edit an existing Discord bot. I discovered that the simplest way to achieve my goal would be to edit the root function at which it generates Random numbers. The relavant snippet of the original code (taken from the dice-expression-evaluator module https://github.com/dbkang/dice-expression-evaluator) is as follows:
Dice.prototype.roll = function () {
var rolls = [];
var sum = 0;
for (var i = 0; i < this.diceCount; i++) {
var roll = random.integer(1, this.sideCount) * this.coefficient;
rolls.push(roll);
sum += roll;
}
return {roll: sum, dice: rolls};
};
This original code works just fine, but doesn't include my desired feature (a simple-but-verbose sort of whitelist.) the 4 variables not defined in that particular code block are rather self-explanatory. My version of the code (slightly edited for privacy reasons) is as follows:
Dice.prototype.roll = function () {
var rolls = [];
var sum = 0;
var range = this.whitelist(); //already tried it with () after whitelist
console.log(range.join(','));
for (var i = 0; i < this.diceCount; i++) {
var roll = random.integer(range[0], range[1]) * this.coefficient; //changed the 2 function arguments, but both are still integers
rolls.push(roll);
sum += roll;
}
return {roll: sum, dice: rolls};
};
Dice.prototype.whitelist = function () {
let user0 = "a";
let user1 = "b";
let user2 = "c";
let user3 = "d";
let user = message.author.id;
let die = this.sideCount;
console.log(user);
console.log(string(die));
if (user==user0) {
var min = Math.ceil(0.76 * die);
var max = die;
} else if (user==user1) {
var min = Math.ceil(0.76 * die);
var max = die;
} else if (user==user2) {
var min = 1;
var max = die;
} else if (user==user3) {
var min = 1;
var max = die;
} else {
var min = 1;
var max = die;
}
return [min, max];
};
The message.author.id variable is available to the function that started the whole function chain 3 scopes up, but in MY version of the code, (even after correcting a few missing semicolons and similarly minute errors) a dice expression that is perfectly functional in the original code generates an "invalid dice expression" error. Other than the introduction of a new variable and the variables in the random.integer call, I see no functional difference between the old and new versions of Dice.prototype.roll. By my understanding, my whitelist function returns an array of integers, and those integers are being injected directly into the random.integer function call in a perfectly reasonable way... I am incredibly confused.
I want to generate an Unique 5 digits ID + 784 at the begining, the constraint, I can execute the script only one time, and I have to avoid the first 100 numbers so It can't be 00100 and lower. Since I use timestamp and I can execute only my script one time how I can handle this ?
I did this it's maybe dumb but at least I tried.
ConcatedID();
function ConcatedID()
{
var uniqID = checkProtectedRange();
if (checkProtectedRange())
{
var BarcodeID = 784 + uniqID;
return BarcodeID;
}
else
checkProtectedRange();
}
function checkProtectedRange()
{
var uniqueID = GenerateUniqueID();
var checkRange = uniqueID.substr(uniqueID.length - 3);
var checkRangeINT = parseInt(checkRange);
if (checkRangeINT <= 100)
return (false);
else
return (true);
}
function GenerateUniqueID()
{
var lengthID = 5;
var timestamp = + new Date();
var ts = timestamp.toString();
var parts = ts.split("").reverse();
var id = "";
var min = 0;
var max = parts.length -1;
for (var i = 0; i < lengthID; ++i)
{
var index = Math.floor(Math.random() * (max - min + 1)) + min;
id += parts[index];
}
gs.log('Generate ID ' + id);
return id;
}
Without being able to track previously used IDs, you're left with chance to prevent duplicates. Your shenanigans with Date doesn't really change that. See the birthday problem.
Given that, just follow the most straight-forward method: Generate a random string consisting of five digits.
function GenerateUniqueID() {
return ('0000'+(Math.random() * (100000 - 101) + 101)|0).slice(-5);
}
Or, if you want just the final integer with constraints applied:
function GenerateUniqueID() {
return (Math.random() * (78500000 - 78400101) + 78400101)|0;
}
This is my current assignment :
Add a method that will increase the value of one of the numeric properties.
Add a method that will decrease the value of the same numeric property.
Create a for loop after creating an instance of the character. The loop will iterate 100 times.
Inside the loop call one of the methods based on a random number from zero to 3. Using a switch statement, if the value is 0 then call the method that losses; 1 don’t call anything; 2 call the method that gains.
Here is my current coding. I know I'm doing something wrong. I just can't figure out what I am doing wrong with the switch statement.
var BR = "<br />";
function person(name, sandwiches) {
this.name = name;
this.sandwiches = sandwiches;
function jump() {
var text = " leaps over an obstacle.";
return fname + text;
}
function run() {
var text = " runs as fast as they can";
return fname + text;
}
function dodge() {
var attack = math.random();
var att = math.round(attack);
var defense = math.random();
var def = math.round(defense);
if(att > def) {
return "You missed";
}
else {
return "You dodged";
}
}
function date() {
var today = new Date();
return today.toDateString();
}
function shout() {
var word = "Oh no";
return word.toUpperCase();
}
this.addSandwich = function (sandwiches) {
sandwiches = sandwiches + 1;
return sandwiches;
};
this.loseSandwich = function (sandwiches) {
sandwiches = sandwiches - 1;
return sandwiches;
};
}
var character = new person("Jerry", 1);
for(i=0; i < 100; i++) {
var random = Math.floor(Math.random() * 3);
switch(random) {
case 0:
character.loseSandwich(character.sandwiches);
console.log(sandwiches);
break;
case 1:
break;
case 2:
character.addSandwich(character.sandwiches);
break;
}
}
document.write("Name: " + character.name + BR);
document.write("Sandwiches: " + character.sandwiches + BR);
Math.floor(Math.random() * 3) is not what you want.
You want something like Math.random() % 3 to get 0, 1, or 2 every single time
Not sure if this is your problem, but it is at least one of them;
In a few places you have a lowercase math, for example:
function dodge() {
var attack = math.random();
JavaScript is case-sensitive, and it should be Math.random() not math.random()
Another issue is that these functions:
this.addSandwich = function (sandwiches) {
sandwiches = sandwiches + 1;
return sandwiches;
};
do not change the number of sandwiches. You get in a value of sandwiches, add or subtract 1, then return that changed number, but never use the returned result.
You are only changing the value of the variable that was passed in, not changing the number of sandwiches on the instance of the person.
Note that this.sandwiches (the variable on the instance of a person) is not the same variable as sandwiches (the function argument)
I dont think there is any reason to pass the number of sandwiches into those functions, and they could just do:
this.addSandwich = function () {
this.sandwiches = this.sandwiches + 1;
};
or more simply:
this.addSandwich = function () {
this.sandwiches++;
};
Another problem here:
character.loseSandwich(character.sandwiches);
console.log(sandwiches);
The console.log statement is trying to log sandwiches but that is not a variable at that point. You probably wanted console.log(character.sandwiches); However this wouldn't cause an exception, it would just always log undefined.