JavaScript

In JavaScript, type conversion refers to changing a value from one data type to another. It happens in two ways:

• Implicit Conversion (Type Coercion) – done automatically by JavaScript
• Explicit Conversion – done manually by the developer

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📌 1. Implicit Type Conversion (Type Coercion)

JavaScript automatically converts types when needed.

🧪 Example:

let result = "5" + 2;
console.log(result); // "52" (number 2 converted to string)

let result2 = "5" - 2;
console.log(result2); // 3 (string "5" converted to number)

⚠️ Rules:

• + operator converts numbers to strings if one operand is a string
• Other arithmetic operators (-, *, /) convert strings to numbers

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📌 2. Explicit Type Conversion

You control the conversion using built-in functions.

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🔢 Convert to Number

Use Number(), parseInt(), or parseFloat().

✅ Examples:

Number("123");       // 123
Number("abc");       // NaN
parseInt("10.5");    // 10
parseFloat("10.5");  // 10.5

🧠 Special Cases:

Number(true);   // 1
Number(false);  // 0
Number(null);   // 0
Number(undefined); // NaN

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🔡 Convert to String

Use String() or .toString().

✅ Examples:

String(123);          // "123"
(123).toString();     // "123"
String(true);         // "true"
String(null);         // "null"

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🔁 Convert to Boolean

Use Boolean() to convert a value to true or false.

✅ Examples:

Boolean(0);        // false
Boolean("");       // false
Boolean(null);     // false
Boolean(undefined);// false
Boolean(NaN);      // false

Boolean("hello");  // true
Boolean(1);        // true

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📋 Truthy and Falsy Values

🔴 Falsy Values (evaluated as false):

• 0
• "" (empty string)
• null
• undefined
• NaN
• false

🟢 Everything else is truthy

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🔍 Example: Type Conversion in Action

let x = "10";
let y = 5;

let sum = Number(x) + y;
console.log(sum); // 15 (x is converted to number)

let result = x + y;
console.log(result); // "105" (y is converted to string)

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✅ Summary Table

Conversion	Method(s)	Example
To Number	Number(), parseInt()	Number("10") → 10
To String	String(), .toString()	String(5) → "5"
To Boolean	Boolean()	Boolean(0) → false
Auto Conversion	Implicit via operators	"5" + 2 → "52"

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🧠 Best Practices

• Use explicit conversion to avoid unexpected results.
• Be careful with == vs === (the former allows type coercion).

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