I can get random numbers in a custom range, with:
Math.floor(Math.random() * ( maximo - minimo + 1 ) + minimo )
var max = 10,
min = 4,
random = Math.floor(Math.random() * (max - min + 1) + min);
console.log(random);But how can I get numbers between a certain range, including decimals between them?
For example, I want to get the numbers 1 - 3 , and the first decimal included, the options would be:
[1, 1.1, 1.2, 1.3 .... 3] ,
How can I do it in JavaScript?
I want to get the array with the smallest result by multiplying all its terms.
The array will be inside another array, to work with them.
My code is:
function _min (arr){
var _reduced = arr.map(cur => {
return cur.reduce((c,i)=> {
return c * i;
});
});
return Math.min(..._reduced);
}
console.log(_min([[4,3,5],[5,2,5]]));I get the values correctly, but how could I get to which array the lowest value obtained belongs to?
In this code, when the length of the array reaches 100, it DOES return 0.
function multiplos(arr) {
if(arr.length > 100) {return arr;}
else {
arr.push(arr[arr.length-1]*2);
return multiplos(arr);
}
}
console.log(multiplos([2]));So why does it not return here as well, but instead returns the expected result? Instead, in the previous example I must return the array, because otherwise it returns 0.
function sum(nums) {
if (nums.length === 0) {
console.log("Sí llegé a 0");
return 0;
} else {
const [first, ...rest] = nums;
return first + sum(rest);
}
}
console.log(sum([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]));Edition:
function multiplos(arr) {
if(arr.length > 100) {return 0;}
else {
arr.push(arr[arr.length-1]*2);
return arr + multiplos(arr);
}
}
console.log(multiplos([2]));According to what Asier has answered me, it is because they add up and indeed here I see it, since apparently what is accumulating is what is before the addition, I mean "return **arr** + multiplos(arr)", even so I have the doubt if it really is like that , and why not return it as an array?
console.log(window.window.window.window.window);why window.window = window? What is it for? Is it a design error?
I'm using a regular expression to prevent characters other than letters from being written to a textarea:
/[A-Za-Z]/ig
but it throws me this error related to the regular expression:
Range out of order in character class
Why does this happen?
window.addEventListener("DOMContentLoaded", checker);
function checker() {
var textArea = document.getElementsByTagName("textarea");
for (let element of textArea) {
element.addEventListener("keypress", event => {
var letra = "which" in event ? event.which : event.keyCode,
patron = /[A-Za-Z]/ig;
if (!patron.test(letra)) {
event.preventDefault();
return false;
}
});
}
}<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
</head>
<body>
<textarea cols="40" rows="10"></textarea></textarea>
</body>
</html>When it comes to making random numbers in Javascript, I have always seen that they use the typical:
Math.floor(Math.random() * (max - min + 1) + min);
And from this doubts arose, why should the difference be multiplied between max y min? , because adding 1it makes the maximum limit inclusive ? and also why do it with Math.floorand not just do it with toFixed(0), so it would be more accurate ?
If in a Array, I look for an element with includes, instead of returning a boolean, how can I return the match, that is, what was the element found ?
var a = ["eeuu","usa"];
var b = "eeuu";
var c = a.includes(b);
console.log(c);Why can't I assign the prototype to c, like this so that it contains the methods of the class Array
c.prototype = Object.create(Array.prototype); // Aquí lo asigno
window.addEventListener('DOMContentLoaded',() => {
var c = document.getElementsByClassName('clases');
c.prototype = Object.create(Array.prototype);
c.forEach(function(clase){
console.log(clase.className);
});
});<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
</head>
<body>
<a class="clases">Enlace 1</a>
<a class="clases">Enlace 2</a>
<a class="clases">Enlace 3</a>
<a class="clases">Enlace 4</a>
</body>
</html>
What is the difference when using .textand .innerHTMLgetting the text?
window.addEventListener('DOMContentLoaded',() => {
var pattern = /^joya[0-9]/,
getting = document.getElementsByTagName('*'),
elements = [];
Array.from(getting).forEach(clase => {
if(pattern.test(clase.className)) elements.push(clase);
});
/* Mostrar */
elements.forEach(i => { /* .text */
console.log('Con .text: ' + i.text);
});
elements.forEach(i => { /* .innerHTML */
console.log('Con innerHTML: ' + i.innerHTML);
});
});<a class='joya1' href='' value="joyita1">joyyy1</a>
<a class='joya2' href='' value="joyita2">joyyy2</a>
<a class='joya3' href='' value="joyita3">joyyy3</a>Why does it tell me that forEach is not a function?
What I do is get the elements with class 'classes' and then assign each one an onclick event, but it doesn't WORK for me
window.addEventListener("DOMContentLoaded", () => {
var i = document.getElementsByClassName('clases');
i.forEach(e => {
e.onclick = () => {alert('BonApetit');};
});
});<a class="clases">Enlace 1</a>
<a class="clases">Enlace 2</a>
<a class="clases">Enlace 3</a>
<a class="clases">Enlace 4</a>
var a1 = setTimeout(function(){});
var a2 = setTimeout(function(){});
var a3 = setTimeout(function(){});
var a4 = setTimeout(function(){});
var a5 = setTimeout(function(){});
if(){
clearInterval(a1);
clearInterval(a2);
// etc..
}If I had many in a code setTimeout, and each of these starts with a variable called "a" + un número, how could I identify all the variables that start with a and then with a number, in order to put them in an array and go through them to apply the clearInterval, instead of doing el clearIntervalto each of them (imagining that there are more than 50 variables would be very tedious).
I've been browsing the internet, but I can't find how to perform an algorithm to find prime numbers.
var cantidad = 100,j=2;
for(var i=2;i<cantidad;i++) {
for(;j<cantidad;j++) {
if(j%i==0 && (i==j || i==1)) {
console.log(j);
}
}
}
I tried the following: Trying from 2, since the prime numbers start from there and in the conditional I practically base it on the fact that if the remainder is 0 , and the divisor is the same number or 1, it would show it on the console, but it does not work.
So what is my mistake and how should it be?
Suppose I got the following return from a function:
return {
x: 199,
y: 200
}
Note: I can't change the return itself.
How can I then from where I receive the return modify it? That is, for example:
I got x:199e y:200and I want to add 20. How can I do it?
(function(){
Math.sqrt(25) == 5 ? return true : return false;
})();I only want to return trueif the root of 25gives 5, and otherwise return false.
What this code does is find the indices of and in a string , then with substring, I only take the part inside the brackets."[""]"
Then I draw them in a canvasaccording to the if:
And everything normal, but sometimes, very rarely, unexpectedly I get the error:
Nothing to repeat error
Why does this happen?
var b = this.name.indexOf("["); // Busca el [
var c = this.name.indexOf("]"); // Busca el ]
var mostrar = this.name.substring(b, c + 1);
mostrar = mostrar.replace(/[\[\]']+/g,'');
var d = c - b;
if(d > 1 && nameDraw && mostrar != '') {
var t = this.name.replace(new RegExp(mostrar, 'g'), '');
t = t.replace(/\[.*?\]/g, '');
drawText(this.x - 4, this.y, t, this._nameSize, false);
drawText(this.x, this.y - 62, mostrar, this._nameSize, false);
}
What is the difference between using window.addEventListenerandwindow.document.addEventListener
window.addEventListener("keydown", function(k){
if(k.altKey) {
alert("Solamente window.addEventListener: Tecla [ALT] PRESIONADA");
}
else {
alert("Solamente window.addEventListener: Tecla [ALT], NO PRESIONADA");
}
}, false);
window.document.addEventListener("keydown", function(k){
if(k.altKey) {
alert("Con window.document.addEventListener: Tecla [ALT] PRESIONADA");
}
else {
alert("Con window.document.addEventListener: Tecla [ALT], NO PRESIONADA");
}
}, false);<html>
<body>
</body>
</html>How does this code work? I would like a detailed explanation if possible and to know where there is documentation about it.
if (!+[]+!+[] == 2) {
document.write('Somos iguales');
}
else {
document.write('Somos distintos');
}
What is the difference between:
function sumar() {
var suma = 0;
var f = 0;
for ( f; f < arguments.length; f++) {
suma = suma + arguments[f];
}
document.write(suma);
}
sumar(2,3,4);
with this:
function sumar() {
var suma = 0;
var f = 0;
for ( f; f < arguments.length; f++) {
suma = suma + arguments[f];
}
return suma;
}
document.write(sumar(2,3,4));
I have the following simple code:
<input id="nick" type="text"/>
<script>
var c = document.getElementById('nick').value
</script>
I need to remove a part of the name, only if it has square brackets []. In other words, if it has this name: 'Hola soy juan [soy pro]', it would look like this: 'Hola soy juan'.
I have the following code:
leaderboard.lengthIt is defined from the server and in my case it is 12
var l = leaderboard.length;
var i = 0;
for ( ; i < l; i++) {
var o = (i + 1) + ". " + name;
}
This will show me the position of the players from 1 to 11
But my problem is that even if leaderboard.lengthit is 11, I want it to show all the positions, but at position 9 it does not show the number 9, that is, only:
1 - Player 1
2 - Player 2
3- Player 3
4- Player 4
5- Player 5
6- Player 6
7- Player 7
8- Player 8
- Player 9
10 - Player 10
11 - Player 11