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Javascript JSON.stringify method removes trailing zero if object has value as x.0 ( like 6.0 ) [duplicate]

I am working on a project where I require to format incoming numbers in the following way:
###.###
However I noticed some results I didn't expect.
The following works in the sense that I don't get an error:
console.log(07);
// or in my case:
console.log(007);
Of course, it will not retain the '00' in the value itself, since that value is effectively 7.
The same goes for the following:
console.log(7.0);
// or in my case:
console.log(7.000);
JavaScript understands what I am doing, but in the end the actual value will be 7, which can be proven with the following:
const leadingValue = 007;
const trailingValue = 7.00;
console.log(leadingValue, trailingValue); // both are exactly 7
But what I find curious is the following: the moment I combine these two I get a syntax error:
// but not this:
console.log(007.000);
1) Can someone explain why this isn't working?
I'm trying to find a solution to store numbers/floats with the exact precision without using string.
2) Is there any way in JS/NodeJS or even TypeScript to do this without using strings?
What I currently want to do is to receive the input, scan for the format and store that as a separate property and then parse the incoming value since parseInt('007.000') does work. And when the user wants to get this value return it back to the user... in a string.. unfortunately.

1) 007.000 is a syntax error because 007 is an octal integer literal, to which you're then appending a floating point part. (Try console.log(010). This prints 8.)
2) Here's how you can achieve your formatting using Intl.NumberFormat...
var myformat = new Intl.NumberFormat('en-US', {
minimumIntegerDigits: 3,
minimumFractionDigits: 3
});
console.log(myformat.format(7)); // prints 007.000

Hi
You can use an aproach that uses string funtions .split .padStart and .padEnd
Search on MDN
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padStart
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padEnd
Here you have an example:
const x = 12.1;
function formatNumber( unformatedNumber) {
const desiredDecimalPad = 3;
const desiredNonDecimalPad = 3;
const unformatedNumberString = unformatedNumber.toString();
const unformatedNumberArr = unformatedNumberString.split('.');
const decimalStartPadded = unformatedNumberArr[0].padStart(desiredDecimalPad, '0');
const nonDecimalEndPadded = unformatedNumberArr[1].padEnd(desiredNonDecimalPad, '0');
const formatedNumberString = decimalStartPadded + '.' + nonDecimalEndPadded;
return formatedNumberString;
}
console.log(formatNumber(x))

easy way to multiply a value to successive substrings in javascript

Good morning, sorry for my poor English.
I'm a neophyte and I'm trying to create a javascript program that, given a string in input, if it finds inside defined substrings it returns a value to each substring and returns the sum of the values ​​found as output. Everything ok here. But I'm finding it difficult to manage the case where in front of the substring that I'm looking for, there's for example "2x" which means that the value of the next substring (or of all subsequent substring) is to be multiplied for 2. How can I write in simple code this exception?
Example:
A1 = 1
M1 = 1
input description = A1-M1
output = 2
input descritpion = 2 x A1-M1
output = 4
Thanks in advance

For more comprehesion, you can find my code below:
let str_description = "2 x A1-M1";
var time_mont = [];
var time_cloa = [];
if(str_description.includes("A1")){
time_mont.push (0.62);
} else {
time_mont.push (0);
}
if(str_description.includes("M1")){
time_mont.push (0.6);
} else {
time_mont.push (0);
}
How can I manage "2 x " subtring?

Declare JavaScript variable only with ' ' marks

I saw one of the masters doing this:
var example = '';
Then later he continued with this:
example += '<div>just a div</div>';
I wanna know if there's any difference from doing this:
var example;
example += '<div>just a div</div>';
I don't really know if by doing the second method I'm doing wrong and I have to code like shown if the first example.
Updated!
Thank you so much for your answers, Ok I got it I need to define my variable to be able to work woth it, but then another question came... This master also is doing this:
var guess;
and then he does:
guess += myfunction( upper );
where myfunction was declared as follows:
function myFunction( upper ){
return Math.floor( Math.random() * upper ) + 1;
}
So, why here is different? Can any of you answer this please?
Thank you!
Second update!
Again Thanks!
I decided to post the whole code the JS master was doing, at this point I don't understand, so probably you'll be able to clear my doubts.
var randomNumber = myFunction( 10 );
var guess;
var attempts = 0;
var answer = false;
function myFunction( upper ){
return Math.floor( Math.random() * upper ) + 1;
}
do{
guess = prompt( "I created a number from 1 till 10, can you guess it?");
attempts += 1;
if( parseInt( guess ) === randomNumber ){
answer = true;
}
}while( ! answer )
document.write( "Took you " + attempts + " attempts to guess the number " + randomNumber);
Please have a look at:
var guess;
and how later is being declared, so why here works perfectly but in my first example I have to put the '' when declaring my variable?
I hope my question is clear enough for you!
Thank you for your time and patient!

When you do:
var example;
example += '<div>just a div</div>';
You end up with:
`"undefined<div>just a div</div>"`
This is because when you don't initialize a variable, it is undefined, which can be converted to a sensible string "undefined" when you try to add it to another string.
When you do:
var guess;
guess += myfunction( upper );
function myFunction( upper ){
return Math.floor( Math.random() * upper ) + 1;
}
You are adding a number to undefined. This results in NaN (not a number) because undefined cannot be converted into a sensible number.
You can check this yourself next time by opening up your browser's developer tools and running the code in the console.
Edit:
When you do:
var guess;
guess = prompt( "I created a number from 1 till 10, can you guess it?");
There's no issue because you are simply assigning a string to the guess variable. In the previous examples you were adding something to a variable, which means if they are different types then JavaScript has to try to do something sensible.

If you don't initialize your variable it has a value of undefined.
In your last example, you are really saying example = undefined + '<div>just a div</div>' and undefined will be converted to a string and output that way. Probably not what you want.
In general it is a good idea to initialize your variables before you use them which is why var example = '' is preferable in this case.

var myvar
myvar += 'asdf'
console.log(myvar) // prints undefinedasdf
var othervar = ''
othervar += 'sdfasdf'
console.log(othervar) // prints sdfasdf

If you don't initialize the variable then it will be undefined
Appending to undefined object doesn't help.
var example = '';
Here you are initializing an empty string to the variable and therefore appending a string to another string will give the desired output of string concatenation.
Output:
"undefined<div>just a div</div>"
"<div>just a div</div>"

Yes there is a difference the first snipet from the master creates a variable example and gives it a default value, the second statement concatinates the value with 'just a div'
.Your code has an error as it is adding a value to a non-existed value as variable example has no default value.

I want to obtain a certain part of text from a large webpage using Javascript, how do I?

There is a certain webpage which randomly generates a number, for example "Frequency : 21". I am trying to create a script which takes the number, 21, and compares it to another variable, then to an if else function. Basically, I've completed most of it, but I can't obtain the number 21. And since it is random, I can't put in a fixed value.
Can anyone help me out?
My code goes like:
setTimeout(MyFunction,5000)
function MyFunction(level,legmin) {
var level = x
var legmin = 49
if (level <= legmin) {
location.reload(true)
}
else {
alert("Met requirements.")
}
where the address of the text I want is:
html>body>div#container>div#contentContainer>div#content>
div#scroll>div#scrollContent>div>div>div#pkmnappear>form>p (x in the code above).

A quick-n-dirty solution without regex.
var lookFor = "Frequency : ";
var text = document.querySelector("#pkmnappear>form>p").textContent;
var level = text.substr(text.indexOf(lookFor) + lookFor.length).split(" ")[0];
This assumes the number will be followed by a space

Why is this bang in the If Then Failing Here

The value in div PermanentHiddenDiv3 can be -11, 1, 6, 12, 17, 18 or 29.
However, at the point in the script where this code exists, the value should
only ever be 18. So, I could go with that.
On the other hand, if I could get this to work with other values being
handled as well, it would be better.
var OMGxAlgebra = function(evt){
var AltReality = document.getElementById("Latent29");
var AreYouSAVED;
var SingleEval = document.getElementById("PermanentHiddenDiv3");
var ThinkingIsAntiSocial = SingleEval.textContent;
OhItIS = ThinkingIsAntiSocial*1;
// You can write this ::
// if(OhItIS==18){
// AreYouSAVED="";
// AltReality.textContent=AreYouSAVED;
// }
if(OhItIS==18){
AreYouSAVED="";
AltReality.textContent=AreYouSAVED;
}
};
The code above works, but the next does not. I thought that in JavaScript
this syntax was valid ???
if(!somevar==X){}
if(!OhItIS==29){
AreYouSAVED="";
AltReality.textContent=AreYouSAVED;
}
The code in context : http://jsfiddle.net/MountainMan72/4gySs/ ... just in case
I am missing some external tripwire.

Use
if (OhItIS != 29){
AreYouSAVED="";
AltReality.textContent=AreYouSAVED;
}
The bang goes before the =
!=

I'm pretty sure you want to use OhItIS != 29
Using !OhItIS == 29 converts OhItIs to a boolean value and compares that to 29. Obviously ends in results that you don't want.
Try this in your browser for verification:
var ohitis = 29;
console.log(!ohitis);
This should print out false;

The precedence rules mean that !x==y parses as (!x) == y, not !(x == y). As the other answers said, use x != y to avoid the problem.