JavaScript Higher order functions

Certainly! Here's a cheat sheet for JavaScript higher-order functions:

1. map():

   • Transforms each element of an array and returns a new array of the same length.

   • Example:

       const numbers = [1, 2, 3, 4];
       const doubledNumbers = numbers.map(function(num) {
         return num * 2;
       });
       // doubledNumbers: [2, 4, 6, 8]
     

2. filter():

   • Creates a new array with only the elements that pass a certain condition.

   • Example:

       const numbers = [1, 2, 3, 4];
       const evenNumbers = numbers.filter(function(num) {
         return num % 2 === 0;
       });
       // evenNumbers: [2, 4]
     

3. reduce():

   • Applies a function to each element of an array, resulting in a single output value.

   • Example:

       const numbers = [1, 2, 3, 4];
       const sum = numbers.reduce(function(acc, num) {
         return acc + num;
       }, 0);
       // sum: 10
     

4. forEach():

   • Executes a function for each element in an array (does not return a new array).

   • Example:

       const numbers = [1, 2, 3, 4];
       numbers.forEach(function(num) {
         console.log(num);
       });
       // Output: 1 2 3 4
     

5. sort():

   • Sorts the elements of an array based on a provided comparison function.

   • Example:

       const numbers = [4, 2, 3, 1];
       const sortedNumbers = numbers.sort(function(a, b) {
         return a - b;
       });
       // sortedNumbers: [1, 2, 3, 4]
     

6. some():

   • Checks if at least one element in an array satisfies a given condition.

   • Example:

       const numbers = [1, 2, 3, 4];
       const hasEvenNumber = numbers.some(function(num) {
         return num % 2 === 0;
       });
       // hasEvenNumber: true
     

7. every():

   • Checks if all elements in an array satisfy a given condition.

   • Example:

       const numbers = [1, 2, 3, 4];
       const allPositive = numbers.every(function(num) {
         return num > 0;
       });
       // allPositive: true
     

These higher-order functions can be used to simplify your code and perform common operations on arrays. Remember to adjust the provided functions according to your specific use case.