JavaScript and Node.js Online Test

Implement the ensure function so that it throws an error if called without arguments or the argument is undefined. Otherwise it should return the given value.

Consider the following package.json for a Node.js application:

{
  "name": "skill-measure-app",
  "private": true,
  "version": "1.0.0",
  "main": "lib/main.js",
  "scripts": {
    "build": "npm run cleanup & npm run test & npm run publish",
    "cleanup": "rm -fr ./lib",
    "test": "jest",
    "publish": "npm publish lib"
  },
  "dependencies": {
     "jest": "^23.0.1",
     "custom-package": "file:../custom-package"
  }
}

Select all the correct statements.

(Select all acceptable answers.)

A Mathematics tutoring web application for kids has a button that highlights all even numbers (in span), using 'yellow' as the background color. Clicking the button again removes the background. All further clicks add or remove the 'yellow' background alternately.

Currently, the button doesn't work as expected. For the given HTML markup and JavaScript function, select all options that will identify and fix the bugs in the JavaScript function:

<div id='numbers'>
 <span>1</span><span>2</span><span>3</span><span>4</span><span>5</span>
 <button id='btn' onclick='toggleEvenColor()'>Toggle even number highlighting</button>
</div>

1: function toggleEvenColor() {
2:   let spanElements = document.querySelectorAll('#numbers span');
3:   spanElements.forEach(function() {
4:     item.style.backgroundColor = 'transparent';
5:   });
6: }

(Select all acceptable answers.)