I have an input field which accepts only integer. And I want to maintain the integer always with two decimal points like 10.00 or 4.00 .
I have already tried toFixed() and toPrecise() already both converts the integer to string.
var anum = 134;
console.log(
anum.toFixed(2), //"134.00"
typeof(anum.toFixed(2)) //"string"
)
I want to maintain it as integer only and not string
Numbers, both in JavaScript and in the abstract, don't have a fixed number of decimal places. (Some kinds of computer numbers do, like Java's BigDecimal, but not the ones in JavaScript.) When you convert the input string to a number, the concept of the number of decimal places that were on the string disappears. If you want to remember that so you can use it when converting back to string, you'll need to store that information (from the input string) separately.
Related
I have a scenario where I need to parsefloat 19 digit string to number.
e.g. parseFloat("1000000000100000043") gives me 1000000000100000000
but the expected output required is 1000000000100000043
This is likely a precision overflow error.
The Number data type (but also int and float in other languages) have a finite number of bits available to represent a number. Typically around 15-16 decimal digits worth.
When length of original number in the string exceeds available precision, such number can no longer be represented by the target data type.
In this case the parseFloat function fails silently. If you want to catch this situation you need to add code to check incoming data or use another function, possibly a custom one.
Alternatively, you can convert the numeric value back to string and compare it with original to detect a discrepancy.
See also a question regarding double.Parse
You are running into how Javascript numbers are stored. See, e.g., here: https://www.w3schools.com/js/js_numbers.asp
You can use a library like decimal.js to work with large, exact numbers. These libraries store the number as string, but allow you to do mathematical operations.
In a javascript code, I have a requirement to format a decimal number to a specific number of decimal places and get its exact string representation. For example, If the number is 999999999.9 and the number of decimal places is 8, then the expected value should be "999999999.90000000"
When the Number.toFixed(8) is used it returns a rounded value which is not what I want. Please refer the below code
var num = 999999999.9
var string_rep = num.toFixed(8)
>> the value of string_rep is "999999999.89999998"
I used num.toString() and tried to manually format the decimal part by adding/removing digits, but it does not work for very small numbers like "0.00000008" as the function toString() returns
the scientific notation, i.e. something like "9e-8"
So what should be the proper approach for this?
Number.prototype.toLocaleString will do the trick
num.toLocaleString('en-US', {minimumFractionDigits: 8, useGrouping: false})//"999999999.90000000"
JavaScript converts all the big numbers into scientific notation.
eg: '90938498237058927340892374089' this string when converted to an integer will come out like this scientific notation '9.093849823705893e+28'.
How can I convert the data type from String to an Integer and avoiding the scientific notation?
In JS all the numbers are treated as floating-point so in end, they end up with precision you can use try BigInt('90938498237058927340892374089') which will give you exact number from string to number.
apart from this, you can also have a look here Javascript - parse string to long
this link might be helpful for you.
Try to use BigInt type:
BigInt('90938498237058927340892374089');
It returns BigInt number with 'n'-literal:
90938498237058927340892374089n
Given a variable
var str = 1;
convert str to output 1.00 as a number and not string.
so the output should be 1.00
and not "1.00"
what javascript operations should I use to do this?.
str.toFixed(2) returns a string and not a number so please..
When you're talking about numbers, there is no difference between 1 and 1.00. So, if it's a number, Javascript will treat them the same. If you want it as 1.00, the only real way to do that is by creating a string of it with something like:
var nnn = 1;
var sss = nnn.toFixed(2));
The presentation of that number (either as a string or direct to output) may be under your control but the number itself is not (other than changing the value of course but, as already mentioned, there is no difference between the values 1, 1.0 or 1e0).
JavaScript only has one kind of number: "number", which is a IEEE-754 Double Precision
See this question to format to 2 decimal places.
I have the problem that when i round a number to 2 decimals the parseFloat() function removes .00 from the number. I have tried
var num = parseFloat(Math.round(19 * 100) / 100).toFixed(2);
The return: num="19.00"
The return i need: num = 19.00
I know 19 = 19.00, but i am using a service that always require two decimals .00
The function returns a string with the right value. When i parse it to float the .00 is removed.
You cannot get 19.00 as float, only as string, because numbers always remove trailing zeros.
Maybe you can show us a bit more code to get an idea, there you need these trailing zeros?
Numbers do and can not hold information about their representation. They are only a numerical value.
When you display a number using window.alert, console.log or similar, you are not looking at a number, but at a string. Those display functions convert numbers to strings before displaying them. Number.toFixed also converts numbers into strings, with the difference being that it rounds them to two decimal places, so you end up with another representation of the same number.
What I am trying to say is that to display a number, you cannot get around converting it to a string. Whether you do it explicitly or the display function does it for you. When you send the number to the service that you are using, you are probably also sending a string (JSON, XML, etc. are always strings once you send them). If you need the value of the number for calculations, use it, then convert it in the end. No matter how, you have to do it in the end if you want those 0's at the end.