js higher order functions

1/* Answer to: "higher order functions javascript" */
2
3/*
4  Higher order functions are functions that operate on other
5  functions, either by taking them as arguments or by returning
6  them.
7  
8  In simple words, A Higher-Order function is a function that
9  receives a function as an argument or returns the function as
10  output.
11  
12  For example; Array.prototype.map, Array.prototype.filter and
13  Array.prototype.reduce are some of the Higher-Order functions
14  built into the language.
15  
16  For more information, go to:
17  https://blog.bitsrc.io/understanding-higher-order-functions-in-javascript-75461803bad
18*/

1function copyArrayAndManipulate(array, instructions) {
2  const output = []
3  for(let i = 0; i < array.length; i++) {
4    output.push(instructions(array[i]))
5  }
6  return output
7}
8
9function multiplyBy10(input) {
10  return input * 10
11}
12
13copyArrayAndManipulate([1, 2, 3], multiplyBy10)

1// function that adds 2 numbers
2function add(number1, number2){
3	return number1 + number2;
4}
5
6// function that multiplies 2 numbers
7function multiply(number1, number2){
8	return number1 * number2;
9}
10
11// higher order function: takes 2 arguments and a function in this case
12function calc(number1, number2, fn){
13	return fn(number1, number2);
14}
15
16// this is how you would use it
17calc(10, 2, add); // you can also use 'multiply' or any other function
18
19// output: 12
20