2-piping.js

/*
  PIPING FUNCTIONS
  ================
  1. Write 3 functions:
  - one that adds 2 numbers together
  - one that multiplies 2 numbers together
  - one that formats a number so it's returned as a string with a £ sign before it (e.g. 20 -> £20)

  2. Using the variable startingValue as input, perform the following operations using your functions all
  on one line (assign the result to the variable badCode):
  - add 10 to startingValue
  - multiply the result by 2
  - format it
  
  3. Write a more readable version of what you wrote in step 2 under the BETTER PRACTICE comment. Assign
  the final result to the variable goodCode
*/

function add(x, y) {
	let sum = (x * 10 + y * 10) / 10;
	return sum;
}
console.log(add(2.4, 5.3));
function multiply(x, y) {
	let multiple = x * y;
	return multiple;
}

function format(number) {
	return `£${number}`;
}

const startingValue = 2;

// Why can this code be seen as bad practice? Comment your answer.
let badCode = format(multiply(add(startingValue, 10), 2));

/* BETTER PRACTICE */

let goodCode = add(startingValue, 10);
goodCode = multiply(goodCode, 2);
goodCode = format(goodCode);

/* ======= TESTS - DO NOT MODIFY ===== 
There are some Tests in this file that will help you work out if your code is working.

To run these tests type `node 2-piping.js` into your terminal
*/

function test(test_name, expr) {
	let status;
	if (expr) {
		status = "PASSED";
	} else {
		status = "FAILED";
	}

	console.log(`${test_name}: ${status}`);
}

test("add function - case 1 works", add(1, 3) === 4);
test("add function - case 2 works", add(2.4, 5.3) === 7.7);
test("multiply function works", multiply(2, 3) === 6);
test("format function works", format(16) === "£16");
test("badCode variable correctly assigned", badCode === "£24");
test("goodCode variable correctly assigned", goodCode === "£24");