JavaScript Type Conversion (original) (raw)
In JavaScript Type Conversion can be defined as converting the data type of the variables from one type to the other manually by the programmer(explicitly) or automatically by the JavaScript(implicitly).
- **Implicit Type Conversion (Coercion): Implicit Type Conversion occurs automatically by the JavaScript.
- **Explicit Type Conversion: Explicit Type Conversion occurs when the programmer manually changes the type of the variables using the function Number(), String(), and Boolean().
Implicit Type Conversion (Coercion)
In JavaScript, the implicit type conversion or coercion conversion can be defined as the automatic conversion of the data type of the variables from one type to another type. Implicit type conversion mostly occurs when we are performing the arithmetic or the logical operations.
**String with Number (Concatenation)
When we add a string with the number, the JavaScript automatically converts the number into a string and performs string concatenation.
JavaScript `
let res = 5 + "5";
console.log(res);
`
**Boolean to Number
When we perform the mathematical operations, then JavaScript automatically converts true to 1 and false to 0.
JavaScript `
let res = true + 1;
console.log(res);
`
Equality Comparison (==)
When we use the equality operator in the JavaScript, it compares them after converting the value into the same data type.
JavaScript `
let res = (5 == "5");
console.log(res);
`
**Automatic Conversion in Logical Operations
In JavaScript, these values are automatically converts undefined, null, "" (empty string), false, NaN, and 0 to false, and all other values to true.
JavaScript `
let res = Boolean("");
let res2 = Boolean("Hello");
console.log(res)
console.log(res2)
`
Explicit Type Conversion
In JavaScript, explicit type conversion can be defined as when we manually change the data type of the variable from one to other using some built-in JavaScript functions. JavaScript provides us the built-in functions for performing the explicit conversion.
Converting to String
In JavaScript, we can convert the value into a string using the String() function, toString(), and by concatenating the empty string.
JavaScript `
let n = 123;
let s1 = String(n);
let s2 = n.toString();
console.log(s1)
console.log(s2)
`
**Converting to Number
In JavaScript, we can convert the value into a number using the Number() function, parseInt(), and parseFloat().
JavaScript `
let s = "123";
let n = Number(s);
let s1 = "12.34";
let n1 = parseFloat(s1);
console.log(n)
console.log(n1)
`
**Converting to Boolean
In JavaScript, we can convert the value into a boolean we can use the Boolean() function.
JavaScript `
let str = "Hello";
let b1 = Boolean(str);
let emptyStr = "";
let b2 = Boolean(emptyStr);
console.log(b1)
console.log(b2)
`
Reasons to Learn JavaScript Type Conversion
- **Data Handling: In JavaScript when we are working with API responses, user inputs and calculations, these type of the operation require type conversion.
- **Prevent Bugs: It is important to understand the type conversion which can help in preventing bugs which occurs when JavaScript implicitly converts value.
- **Code Clarity: By performing the explicit conversion makes our code bug free and more clear.
JavaScript Type Conversion Comparison
| Conversion Type | Implicit Conversion (Coercion) | Explicit Conversion |
|---|---|---|
| String + Number | Automatically converts numbers to strings | Manually convert using String() or .toString() |
| Number + Boolean | Converts true to 1 and false to 0 | Use Number() to explicitly convert |
| String to Boolean | Non-empty strings convert to true, empty to false | Use Boolean() for clarity |
| Number from String | Implicit coercion with + operator | Use Number(), parseInt(), or parseFloat() |