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Code for CTEC3905 04 lab

JavaScript show-hide menu

See comments in the HTML and CSS code for the CSS-only :hover version

Exercise 1: breakpoints and a mobile menu

  1. Create a new repo on GitHub for this lab and copy the URL. Using the command-line in your local CTEC3905 folder, clone the CTEC3905 starter code on GitHub with git clone https://github.com/CTEC3905/starter-code.git, then cd into the cloned folder. In this lab, you’ll create a basic mobile menu using these files, so change the remote in your local repo to your new repo URL using git remote set-url origin your_new_repo_url.git - obviously, replace ‘your_new_repo_url.git’ with your URL(!) - and check that this is correct with git remote -v
  2. Open the folder in Atom and look at the breakpoints in the CSS file - you’ll see the mobile and global styles at the top, then two media queries beginning @media, the first for screen widths over 500px and the next for screen widths over 1000px. If you try this oput in the browser by adjusting the wiondow width, you'll see the background colour change for each of the three widths
  3. Create a 3-item menu in HTML (see the menu code from 02-lab) and style it to appear nicely above the mobile size by adding your CSS inside the @media min-width: 500px breakpoint - you can carefully use parts of the html markup and some CSS styles from 02-lab if you like - if you add flex-direction: column to the nav styles to make the mobile menu vertical. Make sure your browser window is wide enough to show the green or blue background, not the pink (mobile width). Now add a div before the nav tag that just contains the word ‘menu’, and give it a class attribute of menu. In the mobile and global styles (top of the CSS file) add a style block for your .menu class, with a dark background-color, a lighter color for the text, and line-height: 2em just to give it some height
  4. in “styles.css” add a style block inside the first @media min-width: 500px breakpoint that hides .menu using display: none;. The word “menu” should now only appear when the background is pink (at the mobile size). In the opposite way, the nav tag now needs hiding at mobile widths so it appears only above 500px, so add display: none; to the nav tag mobile/global styles, then inside the min-width: 500px breakpoint - again with nav as the selector - use display: flex (as in the lab 02 flexbox styles) and also flex-direction: row to make the menu items line up horizontally. You can use the Chrome developer tools ‘mobile view’ to check your breakpoints if you like, but it won't respond to hover
  5. Now the (slightly) tricky part (see the adjacent sibling combinator). Add a :hover state in the mobile/global styles for the .menu class using display: flex; to show the nav element when the mouse hovers over the menu div. You need the “adjacent sibling combinator” (a plus “+” sign) to target the nav as an adjacent sibling of the .menu:hover state. Test the funcionality in the browser, adjusting width between the mobile (pink) view and above (green or blue) - the menu should be vertical (flex-direction: column;) at mobile but horizontal (flex-direction: row) for wider screens. You should be able to hover over the word “menu” to reveal the nav tag with your menu. Finally, you need to add a nav:hover selector to the same rule (using a comma to separate the two selectors) so that the menu stays visible when you hover over it

Exercise 2: using JavaScript to add a class

  1. Instead of using :hover, you’re now going to use JavaScript to show and hide the menu. In the html file, add an ID of menu-toggle to the menu div tag and an ID of menu-nav to the nav tag. Pull in the JavaScript file just before the closing </body> tag with <script src="js/scripts.js"></script>. In the mobile/global CSS, comment out the entire :hover style block so that display: flex is no longer applied. You’re going to move this rule to a new class that will be activated by JavaScript
  2. Open the empty .js file (or create one in “js/scripts.js”) and add two const variables that store getElementById references to the two new IDs, named like them but in “camelCase”: menuToggle and menuNav (this naming convention is not essential but helps identify things)
  3. Write an ES6 arrow function toggleMenu that (for now) will simply send a message to the console: console.log("called toggleMenu"). Below this, add an event listener to menuToggle that listens for ‘click’ and calls the function toggleMenu. Use the browser inspector mobile view with the console pane open to check that this works - you should see “called toggleMenu” in the console every time you click the menu div (the little counter to the left of the message in the console will increment each time you click)
  4. In the CSS file, you'll be working only in the mobile/global styles at the top. Add a new class .menu-toggle below the .menu style block that contains just one rule: display: flex;
  5. Inside the toggleMenu function, add a classList.toggle() to menuNav with the argument "menu-toggle" in quotes. This can only be called if the menu div is visible and therefore clickable. Test it out in the browser at the mobile size, and expand the width of the browser window to make sure “menu” disappears above the mobile width

Nice work! You have now completed the 02 Lab learning outcomes:

  • understand how @media contains styles that are activated at specified breakpoints
  • using CSS hover to create a mobile menu
  • ES6 arrow function syntax
  • adding and removing a class with JavaScript

If you want to see the menu slide in with a CSS transition, you'll need to use absolute position or margin, as display cannot be animated by CSS.

If you have content blocker on your iPhone you may need to “reload without content blockers” in mobile Safari.

These links will help you with the code: