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Generate random 6 characters based on input

Generate random 6 characters based on input. Like I want to turn 1028797107357892628 into j4w8p. Or 102879708974181177 into lg36k but I want it to be consistant. Like whenever I feed 1028797107357892628 in, it should always spit out j4w8p. Is this possible? (Without a database if possible.) I know how to generate random 6 characters but I dont know how to connect it with an input tbh. I would appreciate any help, thanks.
let rid = (Math.random() + 1).toString(36).substring(7);

You can create a custom hashing function a simple function to your code would be
const seed = "1028797089741811773";
function customHash(str, outLen){
//The 4 in the next regex needs to be the length of the seed divided by the desired hash lenght
const regx = new RegExp(`.{1,${Math.floor(str.length / outLen)}}`, 'g')
const splitted = str.match(regx);
let out = "";
for(const c of splitted){
let ASCII = c % 126;
if( ASCII < 33) ASCII = 33
out += String.fromCharCode(ASCII)
}
return out.slice(0, outLen)
}
const output = customHash(seed, 6)
console.log(output)

It is called hashing, hashing is not random. In your example to get rid:
let rid = (Math.random() + 1).toString(36).substring(7);
Because it is random, it's impossible to be able to produce "consistant result" as you expect.
You need algorithm to produce a "random" consistant result.

Thanks everyone, solved my issue.
Code:
let seed = Number(1028797089741811773)
let rid = seed.toString(36).substring(0,6)
console.log(rid)
Or:
let seed = Number(1028797089741811773)
let rid = seed.toString(36).substring(6)
console.log(rid)

Javascript wrong math [duplicate]

This question already has answers here:
Adding two numbers concatenates them instead of calculating the sum
(24 answers)
Closed 6 years ago.
I'm not sure what's wrong.
There are two variables, cena and uhrada. cena = 10 and uhrada = 279.8. I want to add them but I am getting 279.810 instead of 289.8.
Thanks for any help!
function priplatok(vstup1, vstup2) {
var chid = vstup1;
var cena = vstup2;
var uhrada = document.getElementById('uhr').value;
if (document.getElementById(chid).checked) {
var pridatu = uhrada + cena;
alert(pridatu);
}
}

The reason is that the values you take from the HTML input elements are always strings, even when they look like numbers. You have to first convert them, for instance with parseInt(...) or parseFloat():
var pridatu = parseFloat(uhrada) + parseFloat(cena);
A shorter way is to force conversion with a +:
var pridatu = +uhrada + +cena;
Although this is concise, you should probably first check if the input really is numeric. I refer to a popular question "Validate decimal numbers in JavaScript - IsNumeric()".

You get a string from document.getElementById('uhr').value.
If you want to do math, you need to cast the value either with parseInt(string, 10) or with parseFloat(string) to a number, implicit with a unary plus.
Your code:
function priplatok(vstup1, vstup2) {
var chid = vstup1;
var cena = vstup2;
var uhrada = +document.getElementById('uhr').value; // use implicit cast to number
if (document.getElementById(chid).checked) {
var pridatu = uhrada + cena;
alert(pridatu);
}
}

Thats because the values are strings and not numbers.
You have to make them numbers first and then calculate:
var pridatu = parseInt(uhrada) + parseInt(cena);

Convert comma's into periods js

So I'm trying to make a calculation but it obviously wont calculate with ',' in the numbers. I want to change these vars and make the ',' into '.' using javascript
oldSum.value = '48,35'
newSum.innerHTML = '€43,40'
var oldSumPre = oldSum.value;
var oldStripped = oldSumPre.replace(/,/g, ".");
var newSumPre = newSum.innerHTML;
var newStripped = newSumPre.replace(/,/g, ".");
bedrag.innerHTML = oldStripped - newStripped;
Is what Im doing right now.. but it changes bedrag.innerHTML into NaN

var str = "R,e,p,l,a,c,e";
var res = str.replace(/,/g, ".");
alert (res);

Suppose your variable is vNum. You need to replace all commas with '.' using this
vNum = vNum.replace(",", ".");

In general you could use a localization / internationalization library, which will solve some other tasks you are likely to run into as well.
For example this one:
https://github.com/jquery/globalize/blob/master/doc/api/number/parse-number.md
Snippet:
Globalize.locale( "es" );
Globalize.parseDate( "3,14" ); // 3.14

How to add one to a variable to make 2 not 11

Currently this makes 11. It's for a slideshow and the var "n" equals 1 by default
function forward() {
document.getElementsByClassName("img")[0].setAttribute("class","imgout");
setTimeout( function() {
var n1 = document.getElementById("img").getAttribute("data-number");
var n=n1+1;
document.getElementById("img").setAttribute("data-number", n);
document.getElementById("img").setAttribute("src", "images/" + n + ".jpg");
document.getElementsByClassName("imgout")[0].setAttribute("class","img");
}, 500)
}

Use parseInt():
var n = parseInt(n1, 10) + 1;

Instead of:
var n=n1+1;
When n1 will be a string, because it came from the DOM, you need to convert n1 to an integer. There are many ways to do this, and really you should probably use a regular expression to validate that n1 contains what you expect first, but that being said you can try any of the following:
var n=parseInt(n1, 10)+1;
var n=(n1*1)+1;
var n=(+n1)+1;
As an aside the regex for validating the input from the DOM might be something such as:
/^-?\d+$/

Use Number():
var n = Number("1");
FIDDLE

parseInt - good choice. Also you can do
var n = n-0+1
Just remember that of you have different types "+" will convert to string and "-" will convert to numbers

Convert n1 to number as it is a string like ~~n1. The ~~n1 form is good if you know you want an integer (a 32-bit integer).
Second way is to use Number() function i.e. Number(n1) will convert n1 value into a string.

var n=parseInt(n)+1;
Documentation
Fiddle

Addition not working in Javascript

I'm really new to Javascript and trying to create a form where I'm running into some trouble...
When I use + it does not add up to the value, instead it just puts it back to back. Ex: 5+10 (510)
Here's my code if you want to take a look at it. I'd appreciate any help since I can't figure this out on my own.
var service = document.getElementById("service");
var serviceprice = service.options[service.selectedIndex].id;
var tech = document.getElementById("tech");
var techprice = tech.options[tech.selectedIndex].id;
var hours = document.getElementById("hours").value;
// The error happens here
var total = techprice * hours + serviceprice;
I also have an html part which the script gets the data from.

That happens whenever you have a string rather than a number. The + operator performs concatenation for strings. Make sure you parse your strings to numbers using parseFloat or parseInt:
var service = document.getElementById("service");
var serviceprice = parseInt(service.options[service.selectedIndex].id, 10);
var tech = document.getElementById("tech");
var techprice = parseInt(tech.options[tech.selectedIndex].id, 10);
var hours = parseInt(document.getElementById("hours").value, 10);
Note that parseInt takes an argument to specify the base. You almost always want base 10.

Try changing this line:
var total = techprice * hours + serviceprice;
to
var total = techprice * hours + parseFloat(serviceprice);
I suspect 'servicePrice' is a string, and it will then try to concatenate the first value (let's say: 100) with the second value (which is, not a number, but a string, let's say 'test'), the result being '100test'.

Try to convert the string to int first with parseInt or to float with parseFloat

This is not especially elegant, but I find it simple, easy, and useful:
var total = -(-techprice * hours - serviceprice);
or even:
var total = techprice * hours -(-serviceprice);
They both eliminate the ambiguous + operator.