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Javascript: how to get micronumbers in decimal format

I have simple function that calculates number of decimals,
eg. _d(0.01) = 2, _d(0.001) = 3 and so on.
We added some new coins to our system that have 0.00000001 quantity and function broke.
Here is why:
0.00000001.toString() = 1e-8, so I cant split it it by '.' and calculate length of second part as I did before.
So the question is - how to get string '0.00000001' out of 0.00000001 number easiest way.
EDIT
I didnt mean exactly '0.00000001', I meant any micronumber to decimal without exp. Some function _d(x) that would work _d(0.000000000012) = '0.000000000012'and so on. What usually toString() does to large (but not too large) numbers.

Use toFixed() with a large number of digits, then count the number of zeroes after the decimal point.
function _d(num) {
var str = num.toFixed(100);
var fraction = str.split('.')[1];
var zeros = fraction.match(/^0*/)[0].length;
return zeros + 1;
}
console.log(_d(0.1));
console.log(_d(0.01));
console.log(_d(0.000000001));

Do you want some thing like this
function decimalPlaces(num) {
var match = (''+num).match(/(?:\.(\d+))?(?:[eE]([+-]?\d+))?$/);
if (!match) { return 0; }
return Math.max(
0,
// Number of digits right of decimal point.
(match[1] ? match[1].length : 0)
// Adjust for scientific notation.
- (match[2] ? +match[2] : 0));
}
console.log(decimalPlaces(0.000000001))

First off, I got some inspiration for this answer from here:
How to avoid scientific notation for large numbers in JavaScript?
You can convert the number to a strong and then check for str.indexOf("e"). If true, then just return the scientific notation part of the string. For example:
function _d() {
// your current function here
if (str.indexOf("e")) {
var something = str.split("-")[1];
return something;
}
}
EDIT: I was working on this before your last comment to me, so this returns a string of the number, which I thought was what you wanted.
Leaving aside the point about significant digits, which is meaningful and correct but does not solve your problem, try this. We take the number, convert to string, if that string is not scientific notation then the answer is trivial. If it is scientific notation, then split the string twice (once on "e-" and then split the zeroth array on "." Add str[1]-1 zeroes to the lead of the number and add the digits to the end.
function _d(arg) {
var str = arg.toString();
if (str.indexOf("e-")) {
var digits = str.split("e-")[0];
var zeroes = str.split("e-")[1];
var zero = Number(zeroes);
var each = digits.split(".");
var something = "0.";
for (var i = 0; i < zeroes-1; i++) {
something += "0";
}
for (var j = 0; j < each.length; j++) {
something = something + each[j];
}
return something;
}
}
This won't work with very large numbers or very small negative numbers. And its pretty convoluted.

The other way is to use .toString() and then look for .length-2(2 characters - '0.'. It should give you the number of zeros.
The advantage of this method is you don't need to know the number of maximum decimals in the number.

To keep it as the full decimal:
Number(0.000001)
// 0.000001
To show it as a string:
0.000001.toFixed(6)
// "0.000001"

Number converted in 1e+30

How to convert 1e+30 to 1000000000000000000000000000000
I want number as it is entered by User do not convert like 1e+30.
How can achieve this? Is there any way to display actual digits after parse it to float or int?

The core library doesn't give you any support for numbers that don't fit into the native number type, so you'll probably want to use a third party library to help you with large decimals.
For example, https://mikemcl.github.io/decimal.js/
new Decimal('1e+30').toFixed()
// "1000000000000000000000000000000"

You may use toLocaleString
(1000000000000000000000000000000).toLocaleString("en-US", { useGrouping: false })

You can make use of new Array() and String.replace, but it will only be in the form of String
function toNum(n) {
var nStr = (n + "");
if(nStr.indexOf(".") > -1)
nStr = nStr.replace(".","").replace(/\d+$/, function(m){ return --m; });
return nStr.replace(/(\d+)e\+?(\d+)/, function(m, g1, g2){
return g1 + new Array(+g2).join("0") + "0";
})
}
console.log(toNum(1e+30)); // "1000000000000000000000000000000"
Now it's more robust as it doesn't fail even if a really huge number such as 12e100 which will be converted to 1.2e+101, is provided as the . is removed and the last set of digits decremented once. But still 100% accuracy can't be ensured but that is because of limitations of floatation maths in javascript.

Javascript: Convert a string representation of money to Number

Lets say I have an amount in string format like this:
amount = '12,000.00'
I want to convert it into a Number (Javascript) or a float.
parseFloat(amount) // this gives me 12 as a result
Number(amount) // this gives me NaN as a result
Other solution I thought was this:
parseFloat(amount.replace(/[,]/g, ''))
This works fine. But the problem here is the Locale.
This would fail when the amount is € 12000,00.
Here ',' has altogether a different meaning.
I looked around for a good solution but couldn't. I am looking for a generalized solution.

This is not that easy, as you can't exactly know what's the delimiter for thousands and what for the decimal part
Consider "12.000.000" is it 12000.000 === 12000 or 12000000?
But if you would set the requirement that the last delimiter is always the decimal delimiter -
meaning if at least one delimiter is given, the last one has to be the decimal delimiter, *if the digits following, don't exceed a defined length.
Then you could try the following
Edit
(see the revs if you're interested in the old function)
I put in the ability to define the max length of digits after the last delimiter "," or "." up until it is treated as float, after that its returned as integer
var amounts = ["12000","12.000,00", "12,000.00", "12,000,01", "12.000.02", "12,000,001"];
formatMoney.maxDecLength = 3; //Set to Infinity o.s. to disable it
function formatMoney(a) {
var nums = a.split(/[,\.]/);
var ret = [nums.slice(0, nums.length - 1).join("")];
if (nums.length < 2) return +nums[0];
ret.push(nums[nums.length - 1]);
return +(ret.join(nums[nums.length - 1].length < formatMoney.maxDecLength ? "." : ""));
}
for ( var i=0,j;j=amounts[i];i++)
console.log (j + " -> " +formatMoney(j));
Gives the output:
"12000 -> 12000"
"12.000,00 -> 12000"
"12,000.00 -> 12000"
"12,000,01 -> 12000.01"
"12.000.02 -> 12000.02"
"12,000,001 -> 12000001" //as you can see after the last "," there are 3 digits and its treated as integer
Another JSBin

You can get the local decimal delimiter in this manner:
1.1.toLocaleString().substr(1,1)
Before parse float, you could make sure the string contains nothing but numbers, possibly a minus sign, and the local decimal delimiter.

The truth is, you'll never know the format. 12,345. Is that 12345, or another locale version if 12.345?
However, if you have consistent decimals, then you'd be able to use the lastIndexOf function on a comma and a period will reveal the decimal position and character.
var price = '12,345.67';
var lastPeriod = price.lastIndexOf('.');
var lastComma = price.lastIndexOf(',');
if (lastComma != -1 && lastComma > lastPeriod) {
decimalCharacter = ',';
} else {
decimalCharacter = '.';
}
console.log(decimalCharacter); //. or , based on how the price string looks - see below
If price is 12,345.67, decimalCharacter will be .. If it's 12.345,67, it'll be returned as ,.

Truncate decimal number (as strings) to a fixed number of places

I want to truncate numbers (given as strings) to a fixed number of decimal places. The numbers can be negative (with a minus sign), positive (no sign). I'd prefer to round the numbers properly and keep trailing zeroes. I want the same number of decimal places, no matter how long the whole number is. The numbers will be stored back as strings.
For example:
140.234234234 -> 140.234
1.123123 -> 1.123
-12.789789 -> -12.790

First parse them as floats, then format with toFixed:
var nums = [
"140.234234234", // -> 140.234
"1.123123", // -> 1.123
"-12.789789" // -> -12.790
];
nums.forEach(function(n) {
console.log(parseFloat(n).toFixed(3));
});
http://codepen.io/anon/pen/IvxmA

Any number can be displayed as a fixed decimal place string by using .toFixed:
var num = 140.234234234;
var fixedDecimalPlace = num.toFixed(3); // is "140.234"

function truncate( numberString, trunk ) {
var onpoint = numberString.split('.',2);
var numberStringTruncated = numberString;
if (onpoint.length > 1) {
numberStringTruncated = onpoint[0] + '.' + onpoint[1].substring(0,trunk);
}
return numberStringTruncated;
}
This does not consider rounding or padding. As the other answer suggested, you should use parseFloat followed by toFixed

JavaScript displaying a float to 2 decimal places

I wanted to display a number to 2 decimal places.
I thought I could use toPrecision(2) in JavaScript .
However, if the number is 0.05, I get 0.0500. I'd rather it stay the same.
See it on JSbin.
What is the best way to do this?
I can think of coding a few solutions, but I'd imagine (I hope) something like this is built in?

float_num.toFixed(2);
Note:toFixed() will round or pad with zeros if necessary to meet the specified length.

You could do it with the toFixed function, but it's buggy in IE. If you want a reliable solution, look at my answer here.

number.parseFloat(2) works but it returns a string.
If you'd like to preserve it as a number type you can use:
Math.round(number * 100) / 100

Don't know how I got to this question, but even if it's many years since this has been asked, I would like to add a quick and simple method I follow and it has never let me down:
var num = response_from_a_function_or_something();
var fixedNum = parseFloat(num).toFixed( 2 );

with toFixed you can set length of decimal points like this:
let number = 6.1234
number.toFixed(2) // '6.12'
but toFixed returns a string and also if number doesn't have decimal point at all it will add redundant zeros.
let number = 6
number.toFixed(2) // '6.00'
to avoid this you have to convert the result to a number. you can do this with these two methods:
let number1 = 6
let number2 = 6.1234
// method 1
parseFloat(number1.toFixed(2)) // 6
parseFloat(number2.toFixed(2)) // 6.12
// method 2
+number1.toFixed(2) // 6
+number2.toFixed(2) // 6.12

Try toFixed instead of toPrecision.

function round(value, decimals) {
return Number(Math.round(value+'e'+decimals)+'e-'+decimals);
}
round(1.005, 2); // return 1.01
round(1.004, 2); // return 1 instead of 1.00
The answer is following this link: http://www.jacklmoore.com/notes/rounding-in-javascript/

I used this way if you need 2 digits and not string type.
const exFloat = 3.14159265359;
console.log(parseFloat(exFloat.toFixed(2)));

You could try mixing Number() and toFixed().
Have your target number converted to a nice string with X digits then convert the formated string to a number.
Number( (myVar).toFixed(2) )
See example below:
var myNumber = 5.01;
var multiplier = 5;
$('#actionButton').on('click', function() {
$('#message').text( myNumber * multiplier );
});
$('#actionButton2').on('click', function() {
$('#message').text( Number( (myNumber * multiplier).toFixed(2) ) );
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<button id="actionButton">Weird numbers</button>
<button id="actionButton2">Nice numbers</button>
<div id="message"></div>

The toFixed() method formats a number using fixed-point notation.
and here is the syntax
numObj.toFixed([digits])
digits argument is optional and by default is 0. And the return type is string not number. But you can convert it to number using
numObj.toFixed([digits]) * 1
It also can throws exceptions like TypeError, RangeError
Here is the full detail and compatibility in the browser.

let a = 0.0500
a.toFixed(2);
//output
0.05

There's also the Intl API to format decimals according to your locale value. This is important specially if the decimal separator isn't a dot "." but a comma "," instead, like it is the case in Germany.
Intl.NumberFormat('de-DE').formatToParts(0.05).reduce((acc, {value}) => acc += value, '');
Note that this will round to a maximum of 3 decimal places, just like the round() function suggested above in the default case. If you want to customize that behavior to specify the number of decimal places, there're options for minimum and maximum fraction digits:
Intl.NumberFormat('de-DE', {minimumFractionDigits: 3}).formatToParts(0.05)

float_num = parseFloat(float_num.toFixed(2))

I have made this function. It works fine but returns string.
function show_float_val(val,upto = 2){
var val = parseFloat(val);
return val.toFixed(upto);
}