Number Conversion

• Number(value) → Converts a value to a number.

console.log(Number("42"));   // 42
console.log(Number("3.14")); // 3.14
console.log(Number("hello")); // NaN

• Number.parseInt(string, radix?) → Converts a string into an integer.

console.log(Number.parseInt("42")); // 42
console.log(Number.parseInt("101", 2)); // 5 (binary to decimal)

• Number.parseFloat(string) → Converts a string into a floating-point number.

console.log(Number.parseFloat("3.14")); // 3.14

Number Checking

• Number.isInteger(value) → Checks if a value is an integer.

console.log(Number.isInteger(10));   // true
console.log(Number.isInteger(10.5)); // false

• Number.isNaN(value) → Checks if a value is NaN.

console.log(Number.isNaN(NaN));       // true
console.log(Number.isNaN(10 / "a"));  // true
console.log(Number.isNaN("hello"));   // false

• isFinite(value) → Checks if a value is a finite number.

console.log(Number.isFinite(100));  // true
console.log(Number.isFinite(Infinity)); // false
console.log(Number.isFinite("100")); // false (not converted)

Number Formatting

• Number.toFixed(digits) → Formats a number to a fixed number of decimal places.

let num = 3.14159;
console.log(num.toFixed(2)); // "3.14"
console.log((1.005).toFixed(2)); // "1.00" (watch out for floating-point precision issues)

• Number.toPrecision(digits) → Formats a number to a specified precision.

console.log((123.456).toPrecision(4)); // "123.5"

• Number.toExponential(digits?) → Converts a number to exponential notation.