UPDATE: with a new ES2020 standard released this answer is not entirely correct anymore, see the other answer (from @Mathias Lykkegaard Lorenzen) about BigInt details.

There is only the Number data type in JS that represents numbers.

Internally it is implemented as IEEE 754 double precision floating point number.

What it means is that - technically there is no dedicated data type that represents integer numbers.

Practically it means that we can safely use only numbers that are safely representable by the aforementioned standard. And it includes integer values in the range: [-9007199254740991; 9007199254740991]. Both values are defined as constants: Number.MIN_SAFE_INTEGER and Number.MAX_SAFE_INTEGER correspondingly.

Answer from zerkms on Stack Overflow
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W3Schools
w3schools.com › js › js_number_methods.asp
JavaScript Number Methods
These methods can only be accessed like Number.isInteger(). Using X.isInteger() where X is a variable, will result in an error: TypeError X.isInteger is not a function. The Number.isInteger() method returns true if the argument is an integer.
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MDN Web Docs
developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › Number
Number - JavaScript | MDN
A number literal like 37 in JavaScript code is a floating-point value, not an integer. There is no separate integer type in common everyday use. (JavaScript also has a BigInt type, but it's not designed to replace Number for everyday uses.
Discussions

[AskJS] Its about time javascript should get a "integer" and "float" data type.
JavaScript numbers are double-precision floating-point values, also known as a double in other languages like C. This covers the "float" side of things. Now, a double-precision floating-point value can perfectly represent integers up to 52 bits, which is a lot bigger than the 32 bits an int can typically store in other languages. JavaScript bitwise operators such as & or | or ^ also convert their values to 32-bit integers before doing their work. So, just use regular JavaScript numbers to perform your integer arithmetic, and then throw in a few | 0 operations if you want the rounding / clamping behavior found in other language's 32-bit int types. In other words, everything you want is already present. More on reddit.com
🌐 r/javascript
46
0
August 10, 2022
Is there or isn't there an integer type in JavaScript? - Stack Overflow
I am just starting to learn Javascript and I immediately got confused by seemingly contradictory statements in Mozilla's A re-introduction to JavaScript (JS tutorial). One one hand: "There's no ... More on stackoverflow.com
🌐 stackoverflow.com
Javascript data type integer - Stack Overflow
Good day, I am currently in bit confusion between Data type "number" and data type "Integer" in JavaScript. can anyone explain and gives example. More on stackoverflow.com
🌐 stackoverflow.com
Maximum Integer in Js
Fun question! So in JavaScript, every value with the "number" type is represented under the hood with a 64-bit (or "double-precision") floating point number. Floating point numbers represent a value with a combination of fractions and exponents, which allows them to represent a lot of numbers (with varying degrees of precision), but at the end of the day, the value still has to fit within 64-bits somehow. So there are limits. In this case, the highest number a 64-bit float can possibly represent happens to be 1.7976931348623157e+308 (this number is stored in the constant Number.MAX_VALUE should you ever need to reference it). Your value of 1e+309 is larger than that, so the best a 64-bit float can do is call it Infinity. Under the IEEE 754 floating-point standard (which JavaScript uses), there are some special values, like NaN and Infinity. You can basically think of NaN as "something went wrong with this number" and Infinity as "this number is bigger than I can do anything useful with". Both special values sort of infect anything they touch. The result of any math with NaN is NaN. The result of (almost) any math with Infinity is Infinity. console.log(NaN * 2); // NaN console.log(Infinity - 100); // Infinity console.log(Infinity * 0); // NaN Jumping back to those varying degrees of precision, the highest integer you can represent without losing any precision happens to be a good deal smaller than 1e+308. Since everything is actually a float under the hood, you can only get up to 253 - 1 (or 9,007,199,254,740,991) before you can't trust integer math to work right anymore (that number is stored in the constant Number.MAX_SAFE_INTEGER by the way). console.log(9007199254740991 + 10); // 9007199254741000 Now, the good news for anyone who loves big numbers, is that JavaScript recently added a new primitive type, "bigint". You can make a value a BigInt by adding an n to the end, or by calling BigInt on it. const num = 7; // <-- number const big = 7n; // <-- bigint const int = BigInt(7); // <-- bigint There are two big differences between BigInts and vanilla numbers. They are integers, not floating point. This means you can't represent fractions, but you also never lose precision. They are variable-bit. They start as 64-bit, but if the value gets to large, more bits are added. So with BigInt, we can represent big numbers. let x = 10n ** 309n; // e-notation not supported with BigInt console.log(x); // 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000n And we can safely do big integer math. console.log(9007199254740991n + 10n); // 9007199254741001n But any decimal places just end up getting dropped. console.log(5n / 2n); // 2n More on reddit.com
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August 5, 2022
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MDN Web Docs
developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › Number › isInteger
Number.isInteger() - JavaScript | MDN
If the target value is an integer, return true, otherwise return false. If the value is NaN or Infinity, return false. The method will also return true for floating point numbers that can be represented as integer.
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Soledadpenades
soledadpenades.com › posts › 2024 › quick-conversion-to-integer-in-javascript
Quick conversion to integer in JavaScript | soledad penadés
November 2, 2024 - But if you're only ever expecting integer-shaped numbers and want a quick way of turning DOM string values to integers, >> might be what you need.
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W3Schools
w3schools.com › js › js_numbers.asp
JavaScript Numbers
Javascript numbers are always double (64-bit floating point). Integers (numbers without a period or exponent notation) are accurate up to 15 digits.
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Reddit
reddit.com › r/javascript › [askjs] its about time javascript should get a "integer" and "float" data type.
r/javascript on Reddit: [AskJS] Its about time javascript should get a "integer" and "float" data type.
August 10, 2022 -

After all the improvements/features and fixes which were made to javascript (or precisely ECMAScript) since ES6 (ES2015) till now (ES2022), isn't it about time to fix the ultimate pending weakness i.e. having an Integer and a Float type as well (just like "var" keyword was/is there but they added "let" and "const" as a better semantics and good practice) and not just mashup everything in Number.

Heck, we even got a big int to represent big integers (no floats allowed) but we still don't have Integer's and Floats which are SUPER useful in almost every scenario.

So, why is it still not added and not planned as well? Those are VERY important data types and MOST languages HAVE those data types as they are NEEDED, why is it not planned for ECMAScript? Is it planned? Do you want to see this added?

Find elsewhere
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Mozilla
developer.mozilla.org › en-US › docs › Web › JavaScript › Guide › Data_structures
JavaScript data types and data structures - JavaScript | MDN
July 8, 2025 - Although a number is conceptually a "mathematical value" and is always implicitly floating-point-encoded, JavaScript provides bitwise operators. When applying bitwise operators, the number is first converted to a 32-bit integer.
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SheCodes
shecodes.io › athena › 24057-what-is-an-integer-in-javascript
[JavaScript] - What is an Integer in JavaScript? - SheCodes | SheCodes
Learn about the definition and usage of integers in JavaScript and how they are stored as data types.
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JavaScript.info
javascript.info › tutorial › the javascript language › data types
Numbers
They “read” a number from a string until they can’t. In case of an error, the gathered number is returned. The function parseInt returns an integer, whilst parseFloat will return a floating-point number:
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CoreUI
coreui.io › blog › how-to-check-if-string-is-number-in-javascript
How to check if a string is a number in JavaScript · CoreUI
February 11, 2024 - JavaScript offers multiple pathways to validate if a string is numeric, each with its unique advantages and considerations. By carefully selecting the most appropriate method based on your specific requirements—strict pattern matching with regular expressions, the robustness of Number.isFinite, or the straightforward approach of parsing—the integrity ...
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MDN Web Docs
developer.mozilla.org › en-US › docs › Learn_web_development › Core › Scripting › Math
Basic math in JavaScript — numbers and operators - Learn web development | MDN
The second bit of good news is that unlike some other programming languages, JavaScript only has one data type for numbers, both integers and decimals — you guessed it, Number.
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GeeksforGeeks
geeksforgeeks.org › javascript › javascript-number-reference
JavaScript Number Reference - GeeksforGeeks
1 month ago - EPSILON: Number.EPSILON property shows the difference between 1 and the smallest floating-point number greater than 1. MAX_SAFE_INTEGER: Number.MAX_SAFE_INTEGER property represents the maximum safe integer value in javaScript.
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TutorialsTeacher
tutorialsteacher.com › javascript › javascript-number
JavaScript Numers: Integer, Float, Binary, Exponential, Hexadecimal, Octal
The Number type in JavaScript is double-precision 64 bit binary format like double in C# and Java. It follows the international IEEE 754 standard. The first character in a number type must be an integer value, and it must not be enclosed in ...
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GeeksforGeeks
geeksforgeeks.org › javascript › javascript-number-parseint-method
JavaScript Number parseInt() Method - GeeksforGeeks
1 month ago - Converts a string into an integer value. Supports different number systems using the radix parameter. Stops parsing when a non-numeric character is encountered. JavaScript ·
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James Darpinian
james.darpinian.com › blog › integer-math-in-javascript
Integer math in JavaScript | James Darpinian
July 11, 2022 - Nobody does bitwise operations on floating point numbers. And neither does JavaScript. In fact, JavaScript will (conceptually) first round your 64-bit double to a 32-bit signed integer, do the bitwise operation, and then convert it back to a double precision value.
Top answer
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Fun question! So in JavaScript, every value with the "number" type is represented under the hood with a 64-bit (or "double-precision") floating point number. Floating point numbers represent a value with a combination of fractions and exponents, which allows them to represent a lot of numbers (with varying degrees of precision), but at the end of the day, the value still has to fit within 64-bits somehow. So there are limits. In this case, the highest number a 64-bit float can possibly represent happens to be 1.7976931348623157e+308 (this number is stored in the constant Number.MAX_VALUE should you ever need to reference it). Your value of 1e+309 is larger than that, so the best a 64-bit float can do is call it Infinity. Under the IEEE 754 floating-point standard (which JavaScript uses), there are some special values, like NaN and Infinity. You can basically think of NaN as "something went wrong with this number" and Infinity as "this number is bigger than I can do anything useful with". Both special values sort of infect anything they touch. The result of any math with NaN is NaN. The result of (almost) any math with Infinity is Infinity. console.log(NaN * 2); // NaN console.log(Infinity - 100); // Infinity console.log(Infinity * 0); // NaN Jumping back to those varying degrees of precision, the highest integer you can represent without losing any precision happens to be a good deal smaller than 1e+308. Since everything is actually a float under the hood, you can only get up to 253 - 1 (or 9,007,199,254,740,991) before you can't trust integer math to work right anymore (that number is stored in the constant Number.MAX_SAFE_INTEGER by the way). console.log(9007199254740991 + 10); // 9007199254741000 Now, the good news for anyone who loves big numbers, is that JavaScript recently added a new primitive type, "bigint". You can make a value a BigInt by adding an n to the end, or by calling BigInt on it. const num = 7; // <-- number const big = 7n; // <-- bigint const int = BigInt(7); // <-- bigint There are two big differences between BigInts and vanilla numbers. They are integers, not floating point. This means you can't represent fractions, but you also never lose precision. They are variable-bit. They start as 64-bit, but if the value gets to large, more bits are added. So with BigInt, we can represent big numbers. let x = 10n ** 309n; // e-notation not supported with BigInt console.log(x); // 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000n And we can safely do big integer math. console.log(9007199254740991n + 10n); // 9007199254741001n But any decimal places just end up getting dropped. console.log(5n / 2n); // 2n
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JavaScript uses double-precision floating point values to store numbers. The highest number you can store in this format is 1.7976931348623157e+308 or 2^1024. Anything higher than that is rounded to Infinity, as part of the floating point spec.
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Exploring JS
exploringjs.com › js › book › ch_numbers.html
Numbers • Exploring JavaScript (ES2025 Edition)
There are plans to add something similar to JavaScript: the ECMAScript proposal “Decimal”. Until that happens, we can use libraries such as big.js. Integer numbers are normal (floating point) numbers without decimal fractions: