What are some advanced JavaScript functions I should know?

What are some advanced JavaScript functions I should know?

Some advanced JavaScript functions include closures, higher-order functions, and the use of the 'bind', 'call', and 'apply' methods.

Can you explain closures with an example?

Sure! A closure is a function that retains access to its lexical scope, even when the function is executed outside that scope. For example:

function outerFunction() {
    let outerVariable = 'I am outside!';
    return function innerFunction() {
        console.log(outerVariable);
    };
}

const innerFunc = outerFunction();
innerFunc(); // Outputs: I am outside!

What are higher-order functions?

Higher-order functions are functions that can take other functions as arguments or return them as output. For example:

function map(array, callback) {
    let result = [];
    for (let i = 0; i < array.length; i++) {
        result.push(callback(array[i]));
    }
    return result;
}

const numbers = [1, 2, 3];
const doubled = map(numbers, num => num * 2);
console.log(doubled); // Outputs: [2, 4, 6]

How do 'bind', 'call', and 'apply' differ?

'bind' creates a new function with a specific 'this' context, while 'call' and 'apply' invoke a function immediately with a specified 'this' context. The difference is that 'call' takes arguments individually, while 'apply' takes an array of arguments.