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which are alternative of tofixed() in javascript [duplicate]

Suppose I have a value of 15.7784514, I want to display it 15.77 with no rounding.
var num = parseFloat(15.7784514);
document.write(num.toFixed(1)+"<br />");
document.write(num.toFixed(2)+"<br />");
document.write(num.toFixed(3)+"<br />");
document.write(num.toFixed(10));
Results in -
15.8
15.78
15.778
15.7784514000
How do I display 15.77?

Convert the number into a string, match the number up to the second decimal place:
function calc(theform) {
var num = theform.original.value, rounded = theform.rounded
var with2Decimals = num.toString().match(/^-?\d+(?:\.\d{0,2})?/)[0]
rounded.value = with2Decimals
}
<form onsubmit="return calc(this)">
Original number: <input name="original" type="text" onkeyup="calc(form)" onchange="calc(form)" />
<br />"Rounded" number: <input name="rounded" type="text" placeholder="readonly" readonly>
</form>
The toFixed method fails in some cases unlike toString, so be very careful with it.

Update 5 Nov 2016
New answer, always accurate
function toFixed(num, fixed) {
var re = new RegExp('^-?\\d+(?:\.\\d{0,' + (fixed || -1) + '})?');
return num.toString().match(re)[0];
}
As floating point math in javascript will always have edge cases, the previous solution will be accurate most of the time which is not good enough.
There are some solutions to this like num.toPrecision, BigDecimal.js, and accounting.js.
Yet, I believe that merely parsing the string will be the simplest and always accurate.
Basing the update on the well written regex from the accepted answer by #Gumbo, this new toFixed function will always work as expected.
Old answer, not always accurate.
Roll your own toFixed function:
function toFixed(num, fixed) {
fixed = fixed || 0;
fixed = Math.pow(10, fixed);
return Math.floor(num * fixed) / fixed;
}

Another single-line solution :
number = Math.trunc(number*100)/100
I used 100 because you want to truncate to the second digit, but a more flexible solution would be :
number = Math.trunc(number*Math.pow(10, digits))/Math.pow(10, digits)
where digits is the amount of decimal digits to keep.
See Math.trunc specs for details and browser compatibility.

I opted to write this instead to manually remove the remainder with strings so I don't have to deal with the math issues that come with numbers:
num = num.toString(); //If it's not already a String
num = num.slice(0, (num.indexOf("."))+3); //With 3 exposing the hundredths place
Number(num); //If you need it back as a Number
This will give you "15.77" with num = 15.7784514;

Update (Jan 2021)
Depending on its range, a number in javascript may be shown in scientific notation. For example, if you type 0.0000001 in the console, you may see it as 1e-7, whereas 0.000001 appears unchanged (0.000001).
If your application works on a range of numbers for which scientific notation is not involved, you can just ignore this update and use the original answer below.
This update is about adding a function that checks if the number is in scientific format and, if so, converts it into decimal format. Here I'm proposing this one, but you can use any other function that achieves the same goal, according to your application's needs:
function toFixed(x) {
if (Math.abs(x) < 1.0) {
let e = parseInt(x.toString().split('e-')[1]);
if (e) {
x *= Math.pow(10,e-1);
x = '0.' + (new Array(e)).join('0') + x.toString().substring(2);
}
} else {
let e = parseInt(x.toString().split('+')[1]);
if (e > 20) {
e -= 20;
x /= Math.pow(10,e);
x += (new Array(e+1)).join('0');
}
}
return x;
}
Now just apply that function to the parameter (that's the only change with respect to the original answer):
function toFixedTrunc(x, n) {
x = toFixed(x)
// From here on the code is the same than the original answer
const v = (typeof x === 'string' ? x : x.toString()).split('.');
if (n <= 0) return v[0];
let f = v[1] || '';
if (f.length > n) return `${v[0]}.${f.substr(0,n)}`;
while (f.length < n) f += '0';
return `${v[0]}.${f}`
}
This updated version addresses also a case mentioned in a comment:
toFixedTrunc(0.000000199, 2) => "0.00"
Again, choose what fits your application needs at best.
Original answer (October 2017)
General solution to truncate (no rounding) a number to the n-th decimal digit and convert it to a string with exactly n decimal digits, for any n≥0.
function toFixedTrunc(x, n) {
const v = (typeof x === 'string' ? x : x.toString()).split('.');
if (n <= 0) return v[0];
let f = v[1] || '';
if (f.length > n) return `${v[0]}.${f.substr(0,n)}`;
while (f.length < n) f += '0';
return `${v[0]}.${f}`
}
where x can be either a number (which gets converted into a string) or a string.
Here are some tests for n=2 (including the one requested by OP):
0 => 0.00
0.01 => 0.01
0.5839 => 0.58
0.999 => 0.99
1.01 => 1.01
2 => 2.00
2.551 => 2.55
2.99999 => 2.99
4.27 => 4.27
15.7784514 => 15.77
123.5999 => 123.59
And for some other values of n:
15.001097 => 15.0010 (n=4)
0.000003298 => 0.0000032 (n=7)
0.000003298257899 => 0.000003298257 (n=12)

parseInt is faster then Math.floor
function floorFigure(figure, decimals){
if (!decimals) decimals = 2;
var d = Math.pow(10,decimals);
return (parseInt(figure*d)/d).toFixed(decimals);
};
floorFigure(123.5999) => "123.59"
floorFigure(123.5999, 3) => "123.599"

num = 19.66752
f = num.toFixed(3).slice(0,-1)
alert(f)
This will return 19.66

Simple do this
number = parseInt(number * 100)/100;

Just truncate the digits:
function truncDigits(inputNumber, digits) {
const fact = 10 ** digits;
return Math.floor(inputNumber * fact) / fact;
}

This is not a safe alternative, as many others commented examples with numbers that turn into exponential notation, that scenery is not covered by this function
// typescript
// function formatLimitDecimals(value: number, decimals: number): number {
function formatLimitDecimals(value, decimals) {
const stringValue = value.toString();
if(stringValue.includes('e')) {
// TODO: remove exponential notation
throw 'invald number';
} else {
const [integerPart, decimalPart] = stringValue.split('.');
if(decimalPart) {
return +[integerPart, decimalPart.slice(0, decimals)].join('.')
} else {
return integerPart;
}
}
}
console.log(formatLimitDecimals(4.156, 2)); // 4.15
console.log(formatLimitDecimals(4.156, 8)); // 4.156
console.log(formatLimitDecimals(4.156, 0)); // 4
console.log(formatLimitDecimals(0, 4)); // 0
// not covered
console.log(formatLimitDecimals(0.000000199, 2)); // 0.00

These solutions do work, but to me seem unnecessarily complicated. I personally like to use the modulus operator to obtain the remainder of a division operation, and remove that. Assuming that num = 15.7784514:
num-=num%.01;
This is equivalent to saying num = num - (num % .01).

I fixed using following simple way-
var num = 15.7784514;
Math.floor(num*100)/100;
Results will be 15.77

My version for positive numbers:
function toFixed_norounding(n,p)
{
var result = n.toFixed(p);
return result <= n ? result: (result - Math.pow(0.1,p)).toFixed(p);
}
Fast, pretty, obvious. (version for positive numbers)

The answers here didn't help me, it kept rounding up or giving me the wrong decimal.
my solution converts your decimal to a string, extracts the characters and then returns the whole thing as a number.
function Dec2(num) {
num = String(num);
if(num.indexOf('.') !== -1) {
var numarr = num.split(".");
if (numarr.length == 1) {
return Number(num);
}
else {
return Number(numarr[0]+"."+numarr[1].charAt(0)+numarr[1].charAt(1));
}
}
else {
return Number(num);
}
}
Dec2(99); // 99
Dec2(99.9999999); // 99.99
Dec2(99.35154); // 99.35
Dec2(99.8); // 99.8
Dec2(10265.985475); // 10265.98

The following code works very good for me:
num.toString().match(/.\*\\..{0,2}|.\*/)[0];

This worked well for me. I hope it will fix your issues too.
function toFixedNumber(number) {
const spitedValues = String(number.toLocaleString()).split('.');
let decimalValue = spitedValues.length > 1 ? spitedValues[1] : '';
decimalValue = decimalValue.concat('00').substr(0,2);
return '$'+spitedValues[0] + '.' + decimalValue;
}
// 5.56789 ----> $5.56
// 0.342 ----> $0.34
// -10.3484534 ----> $-10.34
// 600 ----> $600.00
function convertNumber(){
var result = toFixedNumber(document.getElementById("valueText").value);
document.getElementById("resultText").value = result;
}
function toFixedNumber(number) {
const spitedValues = String(number.toLocaleString()).split('.');
let decimalValue = spitedValues.length > 1 ? spitedValues[1] : '';
decimalValue = decimalValue.concat('00').substr(0,2);
return '$'+spitedValues[0] + '.' + decimalValue;
}
<div>
<input type="text" id="valueText" placeholder="Input value here..">
<br>
<button onclick="convertNumber()" >Convert</button>
<br><hr>
<input type="text" id="resultText" placeholder="result" readonly="true">
</div>

An Easy way to do it is the next but is necessary ensure that the amount parameter is given as a string.
function truncate(amountAsString, decimals = 2){
var dotIndex = amountAsString.indexOf('.');
var toTruncate = dotIndex !== -1 && ( amountAsString.length > dotIndex + decimals + 1);
var approach = Math.pow(10, decimals);
var amountToTruncate = toTruncate ? amountAsString.slice(0, dotIndex + decimals +1) : amountAsString;
return toTruncate
? Math.floor(parseFloat(amountToTruncate) * approach ) / approach
: parseFloat(amountAsString);
}
console.log(truncate("7.99999")); //OUTPUT ==> 7.99
console.log(truncate("7.99999", 3)); //OUTPUT ==> 7.999
console.log(truncate("12.799999999999999")); //OUTPUT ==> 7.99

Here you are. An answer that shows yet another way to solve the problem:
// For the sake of simplicity, here is a complete function:
function truncate(numToBeTruncated, numOfDecimals) {
var theNumber = numToBeTruncated.toString();
var pointIndex = theNumber.indexOf('.');
return +(theNumber.slice(0, pointIndex > -1 ? ++numOfDecimals + pointIndex : undefined));
}
Note the use of + before the final expression. That is to convert our truncated, sliced string back to number type.
Hope it helps!

truncate without zeroes
function toTrunc(value,n){
return Math.floor(value*Math.pow(10,n))/(Math.pow(10,n));
}
or
function toTrunc(value,n){
x=(value.toString()+".0").split(".");
return parseFloat(x[0]+"."+x[1].substr(0,n));
}
test:
toTrunc(17.4532,2) //17.45
toTrunc(177.4532,1) //177.4
toTrunc(1.4532,1) //1.4
toTrunc(.4,2) //0.4
truncate with zeroes
function toTruncFixed(value,n){
return toTrunc(value,n).toFixed(n);
}
test:
toTrunc(17.4532,2) //17.45
toTrunc(177.4532,1) //177.4
toTrunc(1.4532,1) //1.4
toTrunc(.4,2) //0.40

If you exactly wanted to truncate to 2 digits of precision, you can go with a simple logic:
function myFunction(number) {
var roundedNumber = number.toFixed(2);
if (roundedNumber > number)
{
roundedNumber = roundedNumber - 0.01;
}
return roundedNumber;
}

I used (num-0.05).toFixed(1) to get the second decimal floored.

It's more reliable to get two floating points without rounding.
Reference Answer
var number = 10.5859;
var fixed2FloatPoints = parseInt(number * 100) / 100;
console.log(fixed2FloatPoints);
Thank You !

My solution in typescript (can easily be ported to JS):
/**
* Returns the price with correct precision as a string
*
* #param price The price in decimal to be formatted.
* #param decimalPlaces The number of decimal places to use
* #return string The price in Decimal formatting.
*/
type toDecimal = (price: number, decimalPlaces?: number) => string;
const toDecimalOdds: toDecimal = (
price: number,
decimalPlaces: number = 2,
): string => {
const priceString: string = price.toString();
const pointIndex: number = priceString.indexOf('.');
// Return the integer part if decimalPlaces is 0
if (decimalPlaces === 0) {
return priceString.substr(0, pointIndex);
}
// Return value with 0s appended after decimal if the price is an integer
if (pointIndex === -1) {
const padZeroString: string = '0'.repeat(decimalPlaces);
return `${priceString}.${padZeroString}`;
}
// If numbers after decimal are less than decimalPlaces, append with 0s
const padZeroLen: number = priceString.length - pointIndex - 1;
if (padZeroLen > 0 && padZeroLen < decimalPlaces) {
const padZeroString: string = '0'.repeat(padZeroLen);
return `${priceString}${padZeroString}`;
}
return priceString.substr(0, pointIndex + decimalPlaces + 1);
};
Test cases:
expect(filters.toDecimalOdds(3.14159)).toBe('3.14');
expect(filters.toDecimalOdds(3.14159, 2)).toBe('3.14');
expect(filters.toDecimalOdds(3.14159, 0)).toBe('3');
expect(filters.toDecimalOdds(3.14159, 10)).toBe('3.1415900000');
expect(filters.toDecimalOdds(8.2)).toBe('8.20');
Any improvements?

Another solution, that truncates and round:
function round (number, decimals, truncate) {
if (truncate) {
number = number.toFixed(decimals + 1);
return parseFloat(number.slice(0, -1));
}
var n = Math.pow(10.0, decimals);
return Math.round(number * n) / n;
};

function limitDecimalsWithoutRounding(val, decimals){
let parts = val.toString().split(".");
return parseFloat(parts[0] + "." + parts[1].substring(0, decimals));
}
var num = parseFloat(15.7784514);
var new_num = limitDecimalsWithoutRounding(num, 2);

Roll your own toFixed function: for positive values Math.floor works fine.
function toFixed(num, fixed) {
fixed = fixed || 0;
fixed = Math.pow(10, fixed);
return Math.floor(num * fixed) / fixed;
}
For negative values Math.floor is round of the values. So you can use Math.ceil instead.
Example,
Math.ceil(-15.778665 * 10000) / 10000 = -15.7786
Math.floor(-15.778665 * 10000) / 10000 = -15.7787 // wrong.

Gumbo's second solution, with the regular expression, does work but is slow because of the regular expression. Gumbo's first solution fails in certain situations due to imprecision in floating points numbers. See the JSFiddle for a demonstration and a benchmark. The second solution takes about 1636 nanoseconds per call on my current system, Intel Core i5-2500 CPU at 3.30 GHz.
The solution I've written involves adding a small compensation to take care of floating point imprecision. It is basically instantaneous, i.e. on the order of nanoseconds. I clocked 2 nanoseconds per call but the JavaScript timers are not very precise or granular. Here is the JS Fiddle and the code.
function toFixedWithoutRounding (value, precision)
{
var factorError = Math.pow(10, 14);
var factorTruncate = Math.pow(10, 14 - precision);
var factorDecimal = Math.pow(10, precision);
return Math.floor(Math.floor(value * factorError + 1) / factorTruncate) / factorDecimal;
}
var values = [1.1299999999, 1.13, 1.139999999, 1.14, 1.14000000001, 1.13 * 100];
for (var i = 0; i < values.length; i++)
{
var value = values[i];
console.log(value + " --> " + toFixedWithoutRounding(value, 2));
}
for (var i = 0; i < values.length; i++)
{
var value = values[i];
console.log(value + " --> " + toFixedWithoutRounding(value, 4));
}
console.log("type of result is " + typeof toFixedWithoutRounding(1.13 * 100 / 100, 2));
// Benchmark
var value = 1.13 * 100;
var startTime = new Date();
var numRun = 1000000;
var nanosecondsPerMilliseconds = 1000000;
for (var run = 0; run < numRun; run++)
toFixedWithoutRounding(value, 2);
var endTime = new Date();
var timeDiffNs = nanosecondsPerMilliseconds * (endTime - startTime);
var timePerCallNs = timeDiffNs / numRun;
console.log("Time per call (nanoseconds): " + timePerCallNs);

Building on David D's answer:
function NumberFormat(num,n) {
var num = (arguments[0] != null) ? arguments[0] : 0;
var n = (arguments[1] != null) ? arguments[1] : 2;
if(num > 0){
num = String(num);
if(num.indexOf('.') !== -1) {
var numarr = num.split(".");
if (numarr.length > 1) {
if(n > 0){
var temp = numarr[0] + ".";
for(var i = 0; i < n; i++){
if(i < numarr[1].length){
temp += numarr[1].charAt(i);
}
}
num = Number(temp);
}
}
}
}
return Number(num);
}
console.log('NumberFormat(123.85,2)',NumberFormat(123.85,2));
console.log('NumberFormat(123.851,2)',NumberFormat(123.851,2));
console.log('NumberFormat(0.85,2)',NumberFormat(0.85,2));
console.log('NumberFormat(0.851,2)',NumberFormat(0.851,2));
console.log('NumberFormat(0.85156,2)',NumberFormat(0.85156,2));
console.log('NumberFormat(0.85156,4)',NumberFormat(0.85156,4));
console.log('NumberFormat(0.85156,8)',NumberFormat(0.85156,8));
console.log('NumberFormat(".85156",2)',NumberFormat(".85156",2));
console.log('NumberFormat("0.85156",2)',NumberFormat("0.85156",2));
console.log('NumberFormat("1005.85156",2)',NumberFormat("1005.85156",2));
console.log('NumberFormat("0",2)',NumberFormat("0",2));
console.log('NumberFormat("",2)',NumberFormat("",2));
console.log('NumberFormat(85156,8)',NumberFormat(85156,8));
console.log('NumberFormat("85156",2)',NumberFormat("85156",2));
console.log('NumberFormat("85156.",2)',NumberFormat("85156.",2));
// NumberFormat(123.85,2) 123.85
// NumberFormat(123.851,2) 123.85
// NumberFormat(0.85,2) 0.85
// NumberFormat(0.851,2) 0.85
// NumberFormat(0.85156,2) 0.85
// NumberFormat(0.85156,4) 0.8515
// NumberFormat(0.85156,8) 0.85156
// NumberFormat(".85156",2) 0.85
// NumberFormat("0.85156",2) 0.85
// NumberFormat("1005.85156",2) 1005.85
// NumberFormat("0",2) 0
// NumberFormat("",2) 0
// NumberFormat(85156,8) 85156
// NumberFormat("85156",2) 85156
// NumberFormat("85156.",2) 85156

Already there are some suitable answer with regular expression and arithmetic calculation, you can also try this
function myFunction() {
var str = 12.234556;
str = str.toString().split('.');
var res = str[1].slice(0, 2);
document.getElementById("demo").innerHTML = str[0]+'.'+res;
}
// output: 12.23

Here is what is did it with string
export function withoutRange(number) {
const str = String(number);
const dotPosition = str.indexOf('.');
if (dotPosition > 0) {
const length = str.substring().length;
const end = length > 3 ? 3 : length;
return str.substring(0, dotPosition + end);
}
return str;
}

Insert a Comma in the thousandths place in outputted number [duplicate]

This question already has answers here:
How to format a number with commas as thousands separators?
(50 answers)
Closed 6 years ago.
I have created a function that takes a number in Imperial units entered into a div and converts that value to metric units in another div. Being relatively new to js, I am now realizing that a thousandths place comma separator does not come standard. I've tried to apply many of the solutions (many of them reg ex's) that I've found but none suit my needs or have worked. Simply put, I am just looking to have both divs outputted numbers have commas separating the thousandths place. Ultimately, these numbers are elevation values expressed in Feet and Meters. Any insight would be greatly appreciated... thanks!
Here is my code:
<body>
<div id="feet" onload="calculateMeter()">2120</div>
<div id="meter"></div>
<script>
var feet = document.getElementById('feet');
var meter = document.getElementById('meter');
function calculateMeter() {
if (feet.innerHTML > 0) {
meter.innerHTML = (feet.innerHTML * 0.3048).toFixed(1);
feet.toString();
feet = feet.innerHTML.replace(/(\d)(\d{3})\,/, "$1,$2.");
}
}
calculateMeter();
</script>
</body>

Here is a simple RegEx solution
function calculateMeter() {
if (feet.innerHTML > 0) {
var m = (feet.innerHTML * 0.3048).toFixed(2);
meter.innerHTML = m.replace(/\B(?=(\d\d\d)+\b)/g, ",");
}
}

It seems your problem is actually just setting the content the DOM element. Using the solution in How to print a number with commas as thousands separators in JavaScript for formatting numbers, all you need is:
function calculateMeter() {
if (feet.innerHTML > 0) {
meter.innerHTML = numberWithCommas*(feet.innerHTML * 0.3048).toFixed(1));
feet.innerHTML = numberWithCommas(feet.innerHTML);
}
}

My function:
function formatNumberWithCommasDec(d) {
d += "";
var c = d.split(".");
var f = c[1];
var a = c.length > 1 ? c[0] + '.' : '.', flag = false;
var g = f.split('').reverse(), y = 1, s = '';
for (var i = g.length - 1; i >= 0; i--) {
flag = false;
var e = g[i];
var h = (y === 3) ? s = s + e + ',' : s = s + e;
console.log(e);
if(y === 3){
y = 1;
flag = true;
} else {
y = y + 1;
}
}
if(flag){
s = s.substring(0, s.length - 1);
} else {
s = s;
}
return a + s;
}
Fiddle: https://jsfiddle.net/6f0tL0ec/1/
Update: found some problems, but everythings good now

JavaScript OnClick Method

I was having trouble with the OnClick method I was learning while creating a game. Every time I enter the value and click the button, it is stuck in a loop, I tried document.write and it works using that, but than it opens a new page instead of showing up on screen.
I am new to the programming community, so any help would be nice.
<body>
<p>Enter an integer between 1-100 here:
<input id="number" type="text" />
</p>
<p>
<button onclick="onclickFunction()" type="button">Enter</button>
</p>
<p id="result"></p>
<script type="text/javascript">
function onclickFunction() {
var a = Math.random();
var b = a * 100;
var c = Math.ceil(b);
var intNumber;
var count = 0;
var bool = false;
do {
do {
intNumber = document.getElementById("number").value;
}
while (intNumber > 100 || intNumber < 0);
if (intNumber > c) {
document.getElementById("result").innerHTML = "Too High " + "</br>";
bool = false
} else if (intNumber < c) {
document.getElementById("result").innerHTML = "Too Low " + "</br>";
bool = false
} else if (intNumber == c) {
document.getElementById("result").innerHTML = "You Win!" + "<br>" + " It took you " + count + " tries";
bool = true
}
count = count + 1
} while (bool !== true);
document.getElementById("result").innerHTML = "Win!";
}
</script>
</body>
Updated:
<script type="text/javascript">
// Declare all your functions first
// These functions expect no parameters and return values.
function onclickFunction()
{
var a = Math.random();
var b = a * 100;
var c = Math.floor(b);
// Input from text box.
var randomNumber = document.getElementById("number").value;
// Output to paragraph.
if (randomNumber < c && randomNumber != c)
{
document.getElementById("result").innerHTML = "Too Low " + "</br>";
}
else if (randomNumber > c && randomNumber != c )
{
document.getElementById("result").innerHTML = "Too High" + "</br>";
}
else if (randomNumber == c)
{
document.getElementById("result").innerHTML = "Win!";
}
// Clear text box for further input.
document.getElementById("name").value = "";
}
</script>
<p>Enter an integer between 1-100 here: <input id="number" type="text" /></p>
<p><button onclick="onclickFunction()" type="button">Enter</button></p>
<p id="result"></p>
</body>

First of all, it is always useful to create a fiddle.
That way people who are reading your question can run your code immediately.
Let's break down the code
var a = Math.random();
var b = a * 100;
var c = Math.ceil(b);
This can be done in a single line, to save variables.
do
{
intNumber = document.getElementById("number").value;
}
while (intNumber > 100 || intNumber < 0);
I'm not a big fan of using do/while loops this way, although it can come handy when you want to run the do code at least once, like now.
This loop keeps running when the number is bigger than 100, or smaller than 0. So if I pick an incorrect number that means my browser crashes.
if (intNumber>c){
document.getElementById("result").innerHTML = "Too High " + "</br>";
bool = false
}else if (intNumber<c){
document.getElementById("result").innerHTML = "Too Low " + "</br>";
bool = false
}else if (intNumber == c){
document.getElementById("result").innerHTML = "You Win!" + "<br>" + " It took you " + count + " tries";
bool = true
}
First you are checking if the guess is bigger than the answer, than if it's smaller. That means that the last check if it's equal is unnecessary, since that is the only option left. You can just use an else here.
Also try to be consistent with your spacing and where you place your curly brackets.
do{
//Stuff
}
and
do
{
//Stuff
}
Are both valid ways to use brackets, but stick to one style or your code will get too confusing.
count = count + 1
A small oversight here is that the count starts at 0. So when you guess the number in a single try, it will say you have done it in 0 tries.
while (bool !== true);
document.getElementById("result").innerHTML = "Win!";
}
All the previous code will be done until bool becomes true. The problem here is that if I entered a wrong number (or an invalid number). The program will keep running the if statement which requires a lot of computer power since it never stops. It is impossible to change your guess and the page crashes, because the browser is stuck in the while loop.
The simplest solution for this is to calculate if the new guess was correct when the player inputs a new number. So when onClickFunction is called again.
That way you never have to use a while loop. Although you have to calculate the random number somewhere else.
I hope that helped, if you have any question let me know!

PESEL checksum validation(Javascript/HTML)

Im a student currently studying from home and im seriously stuck on a Checksum problem. The script is supposed to validate the PESEL(Polish equivilant of a social security number i think), Anyway the checksum works as follows for
PESEL: 70051012347
PESEL:7,0,0,5,1,0,1,2,3,4 (7)
(Multiply each Pesel number by its corresponding check number)
CHECK:1,3,7,9,1,3,7,9,1,3
(Sum Each number)
SUM: + 7,0,0,45,1,0,7,18,3,12 =93
MOD: 93 MOD 10 = 3
10 - 3 = 7(last digit of pesel)
Where the MOD 10 doesn't equal 0, the result of sum%10 is subtracted from 10 and then matched with the final digit in the original number, if they match its good, if not its bad. All i need to have is a good or bad result.
I'm pretty sure I have all of this fine in my code and there's a simple solution i just cant see it. Any help at all would be massively appreciated.
<html>
<head>
<meta charset="utf-8">
<title>Pesel Checker</title>
<script type="text/javascript">
function peselgood(y)
{
//sample PESEL's
//type 1
//70051012347
//02070803628
//07020803628
//type 2
//83102570819
if (y.length == 11)
{
var arr = [1,3,7,9,1,3,7,9,1,3];
var sum = 0;
//hold original number
var a = parseInt(y);
//First 10 digits without check number and convert to array
y = y.substring(0,9);
y = parseInt(y);
var arr1 = new Array(10);
arr1 = y;
//muliply pesel digits by checksum digits
for (var i = 0; i < 10; i++)
{
sum += arr[i] * arr1[i];
}
sum = sum%10;
if (sum !== 0)
{
sum = 10-sum;
if(sum != a[10])
{
return false;
}
else
{
return true;
}
}
}
else
{
return false;
}
}
function checkpesel()
{
num = document.getElementById("peselfield").value
if (peselgood(num))
{
document.getElementById("peselfield").style.background="#00ff00";
}
else
{
document.getElementById("peselfield").style.background="#ff6666";
}
}
</script>
</head>
<body>
<div>
Check Sum Template
<br/><br/>
<form name="form">
PESEL:
<input type="text" id="peselfield" value="70051012347" /> <button type="button" onclick="checkpesel()">Check</button>
<br/><br/>
</form>
</div>
<br/><br/>
</body>
</html>

You have made a couple of mistakes. If you step through your code using a JavaScript debugger, you will find out exactly what goes wrong. The most important fact is, that you don't have to convert a string to an array of integers. JavaScript automatically understands when to convert a character to an integer.
This is my solution:
function peselgood(y)
{
if (y.length == 11)
{
var arr = [1,3,7,9,1,3,7,9,1,3];
var sum = 0;
//muliply pesel digits by checksum digits
for (var i = 0; i < 10; i++)
{
sum += arr[i] * y[i];
}
sum = sum%10 == 0 ? 0 : 10-sum%10;
return sum == y[10];
}
else
{
return false;
}
}

function checksum(p) { let i, s = +p[ i = 10 ]; while( i-- ) s += "1379"[ i % 4 ] * p[i]; return ! ( s % 10 ); }
<input id="pesel" placeholder="PESEL" autofocus>
<input type="button" value="check" onclick="alert( checksum(pesel.value) ? 'Ok' : 'Bad' )">

The button doesn't work

<body>
<input id="input"></input>
<button id="button" onclick="evaluate()">Submit</button>
<br>
<p id="id"></p>
</body>
<script>
var a = 1;
var b = 100;
var z = Math.floor(Math.random() * (b-a)) + a;
document.getElementById("id").innerHTML = ("Pick a number between 1 and 100. I will try to guess it. I think it's " + z + ".");
var y = document.getElementById("input").value;
function evaluate() {
var y = document.getElementById("input").value;
if (y == 0) {
a = x + 1;
z = (a+b)/2;
if (z%2==1) {
z = z-0.5
}
document.getElementById("id").innerHTML = ("Now I think it's " + z);
stopEvent();
}
if (y == 2) {
b = x - 1;
z = (a+b)/2;
if (z%2==1) {
z = z-0.5;
}
document.getElementById("id").innerHTML = ("Now I think it's " + z);
stopEvent();
}
if (y == 1) {
document.getElementById("id").innerHTML = ("Yay! I'm so smart.");
stopEvent();
}
}
</script>
When I click on the button it doesn't think of another integer, it does nothing. I can't find any typos. This program is supposed to guess your number in 7 guesses. You think of a number between 1 and 100, and it first chooses a random integer 1-100, then you tell it if it's too high or too low, then it resets its range according to what you told it, and it chooses another integer, and another, until it narrows down to 1 integer.

Your variable x is never defined. You jump right into using x in a calculation when it is undefined. What is x supposed to be? Once you define x everything should work.
a = x + 1; // What is x?
If you do not define x then your function evaluate() will break.

evaluate() is a predefined method available, so change the name of your method name if you see a conflict.
Now as mentioned by mwilson, you are using variable x without declaring it with some value.
I guess you have already defined stopEvent() in your code or else you will get an error there also.