Exclusive tips every week

Hey all!

Not a lot new from me this week, but I've got some JS and Vue tips for you, like always.

Enjoy your week!

— Michael

🔥 Proxy Basics

Proxies are one of the strangest but most interesting parts of Javascript.

It's a fancy wrapper that lets us create lightweight reactivity systems like in Vue, and so much more.

Defining a proxy is simple. We just need to create a handler object, and then use it on an object:

const handler = {
  get(target, prop, receiver) {
    return 'proxied!';
  },
};

const someObj = {
  hello: 'world',
};

const proxy = new Proxy(someObj, handler);

console.log(proxy.hello) // proxied!

It lets us intercept property accesses with the get "trap", so we could force any object to use our own logging method:

const handler = {
  get(target, prop, receiver) {
    return () => {
      if (typeof target[prop] !== "function") return;

      // Force the method to use our own logging method
      const consoleLog = console.log;
      console.log = (msg) => {
        consoleLog(`[${prop}] ${msg}`);
      };

      target[prop]();

      console.log = consoleLog;
    };
  },
};

const someObj = {
  hello() {
    console.log('world');
  }
}

const proxy = new Proxy(someObj, handler);

proxy.hello() // [hello] world

We can also intercept when a property is set, prototypes are accessed, and many more things.

You can find a complete list on MDN:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy

🔥 Simplify Styling with Default Slot Wrappers

When using slots in Vue, you might want to apply default styling to ensure consistent appearance across uses.

Instead of requiring slot content to be wrapped every time, you can include the styling wrapper within the slot's component:

<!-- StyledSlot.vue -->
<template>
  <div class="default-styles">
    <slot />
  </div>
</template>

Now, when you use the StyledSlot component, the default styles are automatically applied without extra markup:

<template>
  <StyledSlot>
    Slot content with default styling
  </StyledSlot>
</template>

It's a simple thing, but it makes a difference across a whole app.

Be mindful of the type of slot you're creating—layout slots should not include styling, while content slots should.

This practice prevents unnecessary CSS from complicating your layout and ensures a clean, consistent look for your components' content.

🔥 Fine-grained Loading API in Nuxt

In Nuxt we can get detailed information on how our page is loading with the useLoadingIndicator composable:

const {
  progress,
  isLoading,
} = useLoadingIndicator();

console.log(`Loaded ${progress.value}%`); // 34%

It’s used internally by the <NuxtLoadingIndicator> component, and can be triggered through the page:loading:start and page:loading:end hooks (if you’re writing a plugin).

But we have lots of control over how the loading indicator operates:

const {
  progress,
  isLoading,
  start,      // Start from 0
  set,        // Overwrite progress
  finish,     // Finish and cleanup
  clear       // Clean up all timers and reset
} = useLoadingIndicator({
  duration: 1000,  // Defaults to 2000
  throttle: 300,   // Defaults to 200
});

We’re able to specifically set the duration, which is needed so we can calculate the progress as a percentage. The throttle value controls how quickly the progress value will update — useful if you have lots of interactions that you want to smooth out.

The difference between finish and clear is important. While clear resets all internal timers, it doesn’t reset any values.

The finish method is needed for that, and makes for more graceful UX. It sets the progress to 100, isLoading to true, and then waits half a second (500ms). After that, it will reset all values back to their initial state.

📜 The Difference Between a Post Flush Watcher and nextTick in Vue

Both are used to wait for the DOM to update, but they do it in different ways. We'll explore the differences between them and what it all means.

Check it out here: The Difference Between a Post Flush Watcher and nextTick in Vue

📜 Bulletproof Watchers in Vue

Learn how to write bulletproof watchers in Vue, when to use onCleanup and onWatcherCleanup, and how to build reusable cleanup helpers.

Check it out here: Bulletproof Watchers in Vue

💬 Creating complexity

"The purpose of software engineering is to control complexity, not to create it." — Unkown

🧠 Spaced-repetition: Global Properties

The best way to commit something to long-term memory is to periodically review it, gradually increasing the time between reviews 👨‍🔬

Actually remembering these tips is much more useful than just a quick distraction, so here's a tip from a couple weeks ago to jog your memory.

It's possible to add global properties to your Vue app in both Vue 2 and Vue 3:

// Vue 3
const app = createApp({});
app.config.globalProperties.$myGlobal = 'globalpropertiesftw';

// Vue 2
Vue.prototype.$myGlobal = 'globalpropertiesftw';

I would recommend prefixing any global properties with a $.

This helps prevent naming conflicts with other variables, and it's a standard convention that makes it easy to spot when a value is global.

This global property can be accessed directly off of any component when using the Options API:

computed: {
  getGlobalProperty() {
    return this.$myGlobal;
  },
},

Why can't this be used with the composition API?

Because the composition API is designed to be context-free and has no access to this.

Instead, you can create a simple composable to access your globals:

<script setup>
import useGlobals from './useGlobals';
const { $myGlobal } = useGlobals();
</script>

// useGlobals.js
export default () => ({
  $myGlobal: 'globalpropertiesftw',
});

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