)
}
}
)
(
}
{
)
)
(
)
(
(
{
}
)
(
)
}
)
)
{
(
(
)
)
}
)
(
}
AboutAll PostsWarningRandom

Enum Shorthand

  1. const toEnum = (...values) =>
  2.   Object.freeze(values.reduce((acc, curr) => {
  3.     acc[curr] = curr
  4.     return acc
  5.   }, {}))
  6.  
  7. const Graphics = toEnum(
  8.   'circle', 
  9.   'rect', 
  10.   'triangle'
  11. )
  12.  
  13. console.log(Graphics.circle)

I sure dislike fake enums in js. Something like this at least dries things up – but still, yuk! 😀

// javascript // tricks // types

React Vanilla

  1. <style>*{ font-family: sans-serif; margin-bottoM: .5em;}</style>
  2.  
  3. <h3>TODO</h3>
  4. <ul id=todos></ul>
  5. <label>What needs to be done?<br>
  6.   <input id=todo onchange="newTodo()"/><br>
  7. </label>
  8. <button id=add onclick="newTodo()">Add #1</button>
  9.  
  10. <script>
  11.   let count = 1
  12.   function newTodo() {
  13.     if (todo.value.length > 0) {
  14.       todos.innerHTML += `<li>${todo.value}</li>`
  15.       todo.value = ''
  16.       add.innerText = `Add #${++count}`
  17.     }
  18.   }
  19. </script>

I don’t really like React… Don’t get me wrong, I don’t mind it and I even kind of like using it – there’s something fun about it… But it’s surprising to me that UI work is still so bulky… I think React and most other UI libraries are overly complex… Every now and then I do evil style vanilla js versions of the React homepage examples as a sort of rebellion 😀 This is the React version of the above snippet:

  1. class TodoApp extends React.Component {
  2.   constructor(props) {
  3.     super(props);
  4.     this.state = { items: [], text: '' };
  5.     this.handleChange = this.handleChange.bind(this);
  6.     this.handleSubmit = this.handleSubmit.bind(this);
  7.   }
  8.  
  9.   render() {
  10.     return (
  11.       <div>
  12.         <h3>TODO</h3>
  13.         <TodoList items={this.state.items} />
  14.         <form onSubmit={this.handleSubmit}>
  15.           <label htmlFor="new-todo">
  16.             What needs to be done?
  17.           </label>
  18.           <input
  19.             id="new-todo"
  20.             onChange={this.handleChange}
  21.             value={this.state.text}
  22.           />
  23.           <button>
  24.             Add #{this.state.items.length + 1}
  25.           </button>
  26.         </form>
  27.       </div>
  28.     );
  29.   }
  30.  
  31.   handleChange(e) {
  32.     this.setState({ text: e.target.value });
  33.   }
  34.  
  35.   handleSubmit(e) {
  36.     e.preventDefault();
  37.     if (this.state.text.length === 0) {
  38.       return;
  39.     }
  40.     const newItem = {
  41.       text: this.state.text,
  42.       id: Date.now()
  43.     };
  44.     this.setState(state => ({
  45.       items: state.items.concat(newItem),
  46.       text: ''
  47.     }));
  48.   }
  49. }
  50.  
  51. class TodoList extends React.Component {
  52.   render() {
  53.     return (
  54.       <ul>
  55.         {this.props.items.map(item => (
  56.           <li key={item.id}>{item.text}</li>
  57.         ))}
  58.       </ul>
  59.     );
  60.   }
  61. }
  62.  
  63. root.render(<TodoApp />);
// dom // globals // hacks // humor // ui

C Style Print with Console.log

  1. console.log('print: %s %i %f %o %s', 'two', 1.4, 1.6, { cool: 321 }, [3, 2, 1]);

outputs: print: two 1 1.6 {cool: 321} 3,2,1

Notice how we are casting a float to an integer and an array to a string in the above example. I personally don’t use this much in javascript, but for someone coming from a C/C-like language this should look familiar and could be very useful.

// javascript // tricks

Interview with Senior JS Developer in 2022

This is extremely good.

// humor // javascript

Destructure in Every Function

  1. // read through the comments of this snippet...
  2.  
  3. function dist1(x1, y1, x2, y2) {
  4.   const dx = x1 - x2
  5.   const dy = y1 - y2
  6.   return Math.sqrt(dx**2 + dy**2)
  7. }
  8.  
  9. function dist2({x1, y1, x2, y2}) {
  10.   const dx = x1 - x2
  11.   const dy = y1 - y2
  12.   return Math.sqrt(dx**2 + dy**2)
  13. }
  14.  
  15. // What's the difference here... well
  16. dist1(50, 50, 100, 100)
  17.  
  18. // vs
  19.  
  20. dist2({ x1: 50, y1: 50, x2: 100, y2: 100 })
  21.  
  22. // so what?
  23.  
  24. // With `dist2` the order of the arguments doesn't matter
  25. // and the arguments are named now as a result of being keys
  26. // in an object
  27.  
  28. // How many times have you changed a core function or method as you're
  29. // working on a project?
  30.  
  31. // Let's see another example:
  32.  
  33. // circle(100, 200, 300, 'red', 'blue', 0, 0)
  34.  
  35. // Can you guess what those arguments are? It's not really a big deal
  36. // and editors help with this, typescript helps with this... but what about:
  37.  
  38. circle({ 
  39.   x: 10, 
  40.   y: 110, 
  41.   radius: 120, 
  42.   fill: 'red', 
  43.   stroke: 'blue', 
  44.   velocityX: 0, 
  45.   velocitY: 0
  46. })
  47.  
  48. // how about...
  49. circle({ radius: 50, fill: 'blue' })
  50.  
  51. // or...
  52. circle({ stroke: 'green', x: 40, velocityX: 1 })
  53.  
  54. // etc...
  55. circle({ 
  56.   radius: 50,
  57.   stroke: 'black', x: 200, 
  58.   fill: 'teal',
  59.   velocityY: 1, velocityX: -1 })
  60.  
  61. // In combination with default arguments we end up with a very easy pattern for functions/methods
  62. // with a complex argument signature. gsap (aka TweenLite/TweenMax) has used this pattern for many
  63. // years. I've seen similar things in many languages...
  64.  
  65. // How does the circle function look?
  66.  
  67. function circle({ 
  68.   x = 0, y = 0, 
  69.   radius = 30, 
  70.   fill = 'black', 
  71.   stroke = 'transparent', 
  72.   velocityX = 0, velocityY = 0}) {
  73.  
  74.   const diam = radius * 2;
  75.  
  76.   const circle = document.body.appendChild(
  77.     Object.assign(
  78.       document.createElement('div'), 
  79.       { style: `
  80.         position: absolute;
  81.         left: ${x}px;
  82.         top: ${y}px;
  83.         width: ${diam}px;
  84.         height: ${diam}px;
  85.         background: ${fill};
  86.         border: 3px solid ${stroke};
  87.         border-radius: 100%;
  88.       `
  89.       }
  90.     )
  91.   )
  92.   if (velocityX != 0 || velocityY != 0) {
  93.     setInterval(() => {
  94.       x += velocityX
  95.       y += velocityY
  96.       circle.style.left = `${x}px`
  97.       circle.style.top = `${y}px`
  98.     }, 16)
  99.   }
  100.   return circle
  101. }
  102.  
  103.  
  104. // here is a golfed distance function - for no reason
  105. d=(a,b,c,d,e=a-c,f=b-d)=>Math.sqrt(e*e+f*f)
  106. console.log(
  107.   dist1(0, 0, 140, 140) ===
  108.   d(0, 0, 140, 140)
  109. )
// functions // humor // javascript // oldschool // tricks
Older Posts
Newer Posts

Recent

Archive

RSS
snippet.zone ~ 2021-24 /// {s/z}