JavaScript Data Types is not directly associated with any value type like other languages (Java, Python,
All programming language has a built-in data structure but with own changes and definition. There is some common data type as Integer, Strings, Boolean, Arrays, etc. Not every language declares varible data types the same way.
In other languages, Data Type is used to define a variable type. This means what kind of value will store in this varible. A data type is a basic fundamental of any programming language.
Where in JavaScript variable need to assign the value not a type before name it like in java. For an example like that -> int x = 19.
JavaScript Data Types
Let’s make it easy by dividing a data type into groups. JavaScript variables can be Statically Typed, dynamically typed, and weakly typed.
Then come to other programming language segregation is mostly like that data type- Primitives and Object type. There is always an argument over the JS is not have any data type (untyped)
Dynamically Typed
In JavaScript Dynamic typing, variable type decide by its value after code runs the code at compiler/interpreter. This means if a value of varible integer then variable will be an integer and if its strings then the variable type is also strings. But varible type can change later when a different type of data type value assigned to it. See below code how it will define.
var a = 10; // int
var b = 'test'; // stringStatically Typed
JavaScript DataTypes are not Statically Typed unless you using a tool Typescript or Flow that compiles to JS code. A Static type means to define a varible with its type. This varible is not easily changeable. Let’s see how to define that.
int x = 99;
string y = 'abc';Weakly Typed
JavaScript is a Weakly typed language. This means it allows one data type to be inferred as another type. See below example of it.
var a = 2 + '4'; // '24'Where trying to add a number with a string and result will be not addition. See the output.
Complete Example
<html>
<head>
<script>
function myFunction() {
var number = 2 + '4';
document.getElementById("myText").innerHTML = number;
}
</script>
</head>
<body onload="myFunction()">
<p>the value for number is: <span id="myText"></span></p>
</body>
</html>Output:
Primitives Data types in JavaScript
There
| Type | Value |
| Boolean | true or false |
| Null | No Value |
| Undefined | A |
| Number | integers, floats, Double, Long etc. |
| String | text (written inside double or single quotes) |
| Symbol | A unique value(new in ECMAScript 6) |
Note: If the
Object type DataTypes in javascript
2 Main object are in JavaScript.
- Object
- Array
Many other objects, don’t confuse with primitive types. For below list act as constructors to create those types. For example Boolean('c') // true.
- Function
- Boolean
- Symbol
- Error
- Number
- String
- RegExp
- Math
- Set
- Date
For example of Object type and Primitive type will see on next tutorial.
Do comment if you have any doubt and suggestion of this article.
Note: The JavaScript DataTypes Examples are tested on Safari browser (Version 12.0.2).
OS: macOS 10.14 Mojave
Version: HECMAScript 2018
How does JavaScript’s dynamic typing impact the development process and code maintenance in large-scale projects?