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Solution
Submitted 22 days ago

Tip calculator made in vanilla JavaScript

sass/scss, bem
P
Alexander3717•310
@Alexander3717
A solution to the Tip calculator app challenge
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Solution retrospective


What are you most proud of, and what would you do differently next time?

I am quite happy with the UX of the calculator, the implementation of the custom tip button, and how I handled invalid inputs. Using regex testing on the keydown event, I made sure that only digits can be entered (and dots/commas if the input allows decimals). The calculator also removes any leading zeros live as you type.

Next time, I would probably use <input type="text"> instead of <input type="number">, because <input type="number"> has some quirks (for example, it returns an empty value if the input is invalid), which made some of the features harder to implement. Or better yet, I would try using an external library for validation and input restrictions instead of doing it all manually.

What challenges did you encounter, and how did you overcome them?

There were many challenges. I will try to describe the biggest ones:

  • The custom button styling and logic

    My solution: a <label> covers the whole custom button. When clicked, it becomes invisible and reveals the custom tip input field under it. It also instantly focuses it, allowing the user to type the custom tip value. In case the user doesn't type anything and clicks away, the custom button returns to its initial state.

  • Giving the custom tip input field a placeholder % symbol that moves live with entered text

    My solution: wrap the input field inside a <div> together with a <span>%</span>. Give the wrapper display: flex, center both elements, and make sure the input is only as wide as the text inside it using JavaScript:

    customTipInput.addEventListener("input", () => {
        const length = customTipInput.value.length;
        customTipInput.style.setProperty("--dynamic-width", `${Math.max(length, 1)}ch`);
    });
    
  • Restrict what the user can type inside the input fields and how many digits can they type before and after decimal dot

    My solution: If you'd like to see the code, it's the restrictInput function in script.js. On input of type text this wouldn't be challenging to do, but browser quirks and differences on <input type="number"> made it frustrating (e.g. when retrieving value from the input field to manipulate it, Chrome returns an empty value if the input is currently invalid, while Firefox returns the last valid one in that case). However, the (hopefully) working code that I reached after many iterations turns out to be fairly simple.

What specific areas of your project would you like help with?

If you test the calculator and notice anything that doesn't feel right, please mention it. It's important to me that it works properly. In case you also take the time to look at the code and have suggestions, don't hesitate to comment; I am happy to hear any feedback.

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Community feedback

  • nerdynischal•190
    @nerdynischal
    Posted 14 days ago

    Everything works really well, liked that the input was restricted to avoid any faulty inputs like letters. It is also identical to the design and really well done.

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How does the accessibility report work?

When a solution is submitted, we use axe-core to run an automated audit of your code.

This picks out common accessibility issues like not using semantic HTML and not having proper heading hierarchies, among others.

This automated audit is fairly surface level, so we encourage to you review the project and code in more detail with accessibility best practices in mind.

How does the CSS report work?

When a solution is submitted, we use stylelint to run an automated check on the CSS code.

We've added some of our own linting rules based on recommended best practices. These rules are prefixed with frontend-mentor/ which you'll see at the top of each issue in the report.

The report will audit all CSS, SCSS and Less files in your repository.

How does the HTML validation report work?

When a solution is submitted, we use html-validate to run an automated check on the HTML code.

The report picks out common HTML issues such as not using headings within section elements and incorrect nesting of elements, among others.

Note that the report can pick up “invalid” attributes, which some frameworks automatically add to the HTML. These attributes are crucial for how the frameworks function, although they’re technically not valid HTML. As such, some projects can show up with many HTML validation errors, which are benign and are a necessary part of the framework.

How does the JavaScript validation report work?

When a solution is submitted, we use eslint to run an automated check on the JavaScript code.

The report picks out common JavaScript issues such as not using semicolons and using var instead of let or const, among others.

The report will audit all JS and JSX files in your repository. We currently do not support Typescript or other frontend frameworks.

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