--- id: 6437124c4c03dd4c8fb35d56 title: Step 21 challengeType: 0 dashedName: step-21 --- # --description-- Declare an `isEven` function, which takes a `num` parameter and returns `true` if the number is even, and `false` otherwise. Use the modulo operator `%` to determine if a number is even or odd. # --hints-- You should declare an `isEven` variable. ```js assert.match(code, /(?:let|const|var)\s+isEven/); ``` You should use `const` to declare your `isEven` variable. ```js assert.match(code, /const\s+isEven/); ``` Your `isEven` variable should be a function. ```js assert.isFunction(isEven); ``` Your `isEven` function should use arrow syntax. ```js assert.match(code, /const\s+isEven\s*=\s*(\([^)]*\)|[^\s()]+)\s*=>/); ``` Your `isEven` function should have a `num` parameter. ```js assert.match(code, /const\s+isEven\s*=\s*(\(\s*num\s*\)|num)\s*=>/); ``` Your `isEven` function should use the modulo operator `%`. ```js assert.match(isEven.toString(), /%/); ``` Your `isEven` function should return `true` for even numbers. ```js assert.isTrue(isEven(2)); assert.isTrue(isEven(1000)); assert.isTrue(isEven(42)); ``` Your `isEven` function should return `false` for odd numbers. ```js assert.isFalse(isEven(1)); assert.isFalse(isEven(333)); assert.isFalse(isEven(777777777)); ``` # --seed-- ## --seed-contents-- ```html Functional Programming Spreadsheet
``` ```css #container { display: grid; grid-template-columns: 50px repeat(10, 200px); grid-template-rows: repeat(11, 30px); } .label { background-color: lightgray; text-align: center; vertical-align: middle; line-height: 30px; } ``` ```js --fcc-editable-region-- --fcc-editable-region-- const sum = nums => nums.reduce((acc, el) => acc + el, 0); const range = (start, end) => Array(end - start + 1).fill(start).map((element, index) => element + index); const charRange = (start, end) => range(start.charCodeAt(0), end.charCodeAt(0)).map(code => String.fromCharCode(code)); window.onload = () => { const container = document.getElementById("container"); const createLabel = (name) => { const label = document.createElement("div"); label.className = "label"; label.textContent = name; container.appendChild(label); } const letters = charRange("A", "J"); letters.forEach(createLabel); range(1, 99).forEach(number => { createLabel(number); letters.forEach(letter => { const input = document.createElement("input"); input.type = "text"; input.id = letter + number; input.ariaLabel = letter + number; container.appendChild(input); }) }) } ```