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AboutAll PostsWarningRandom

Simple Way to Validate CSS Colors

  1. function isColor(col) {
  2.   const cache = isColor[col]
  3.   if (cache != null) {
  4.     console.log('- reading cache')
  5.     return cache
  6.   }
  7.   isColor.el.style = ''
  8.   isColor.el.style.color = col
  9.   return isColor[col] = !!isColor.el.style.color
  10. }
  11. isColor.el = document.createElement('div')
  12.  
  13.  
  14. console.log('is "red" a color?', isColor('red'))
  15. console.log('from the cache: ', isColor('red'))
  16.  
  17. console.log('is "rgbx(1, 2, 3)" a color?', isColor('rgbx(1, 2, 3)'))
  18.  
  19. console.log('is "#0f0" a color?', isColor('#0f0'))
  20.  
  21. console.log('is "hsl(192, 50%, 50%)" a color?', isColor('hsl(192, 50%, 50%)'))
  22. console.log('from the cache: ', isColor('hsl(192, 50%, 50%)'))
  23.  
  24. console.log('is "lab(2000.1337% -8.6911 -159.131231 / .987189732)" ?',
  25.   isColor('lab(2000.1337% -8.6911 -159.131231 / .987189732)'))
  26.  
  27. console.log('is "snippetZone" ?', isColor('snippetZone'))

I find this technique is usually good enough to validate colors…

// color // css // dom // graphics // hacks // hex // html // javascript // tricks

Other Gates from NAND

  1. const nand = ([a, b]) => +!(a & b)
  2.  
  3. const not = ([a]) => nand([a, a])
  4.  
  5. const and = ([a, b]) => nand([nand([a, b]), nand([a, b])])
  6.  
  7. const or = ([a, b]) => nand([nand([a, a]), nand([b, b])])
  8.  
  9. const nor = ([a, b]) => 
  10.   nand([ 
  11.     nand([nand([a, a]), nand([b, b])]), 
  12.     nand([nand([a, a]), nand([b, b])])
  13.   ])
  14.  
  15. const xor = ([a, b]) =>
  16.   nand([
  17.     nand([a, nand([a, b])]),
  18.     nand([b, nand([a, b])])
  19.   ])
  20.  
  21. const xnor = ([a, b]) => 
  22.   nand([ 
  23.     nand([nand([a, a]), nand([b, b])]),
  24.     nand([a, b])
  25.   ])
  26.  
  27.  
  28. const inputs = [
  29.   [0, 0],
  30.   [0, 1],
  31.   [1, 0],
  32.   [1, 1]
  33. ]
  34.  
  35. const testGate = ({ gate, truth, result }) => console.log(
  36.   gate + ' matches truth? ', 
  37.   truth+'' === result+'' ? 
  38.     'yes :D' : `nope :( ${truth} ${result}`
  39. )
  40.  
  41. testGate({
  42.   gate: 'NAND',
  43.   truth: [1, 1, 1, 0],
  44.   result: inputs.map(nand)
  45. })
  46.  
  47. testGate({
  48.   gate: 'NOT',
  49.   truth: [0, 1],
  50.   result: [[1], [0]].map(not)
  51. })
  52.  
  53. testGate({
  54.   gate: 'AND',
  55.   truth: [0, 0, 0, 1],
  56.   result: inputs.map(and)
  57. })
  58.  
  59. testGate({
  60.   gate: 'OR',
  61.   truth: [0, 1, 1, 1],
  62.   result: inputs.map(or)
  63. })
  64.  
  65. testGate({
  66.   gate: 'NOR',
  67.   truth: [1, 0, 0, 0],
  68.   result: inputs.map(nor)
  69. })
  70.  
  71. testGate({
  72.   gate: 'XOR',
  73.   truth: [0, 1, 1, 0],
  74.   result: inputs.map(xor)
  75. })
  76.  
  77. testGate({
  78.   gate: 'XNOR',
  79.   truth: [1, 0, 0, 1],
  80.   result: inputs.map(xnor)
  81. })

Use NAND to create a bunch of other gates 😀 – I used this wikipedia article for reference

// arrays // golfed // humor // javascript // math

Multiplicative Persistence

  1. const multp = (val, count = 1, res) => 
  2.   (res = (val + '').split``
  3.     .reduce((a, b) => a * b, 1) + '').length > 1 ?
  4.       multp(res, count + 1) : count
  5.  
  6.  
  7. console.log('test:', multp(2678789))

Started watching this youtube video from numberphile and instantly made this half-golfed thing

Found this:

f=n=>[n,...n>9?f(eval([...n+''].join`*`)):[]]

By Arnauld over at codegolf.stackexchange

will definitely remember: [...n+'']

// golfed // hacks // humor // javascript // math

Parametric Equation for Rectangle

  1. // from http://math.stackexchange.com/questions/69099/equation-of-a-rectangle
  2. const rect = (px, py, rx, ry, t) => ({
  3.   x: px + rx + rx * (Math.abs(Math.cos(t)) * Math.cos(t) + Math.abs(Math.sin(t)) * Math.sin(t)),
  4.   y: py + ry + ry * (Math.abs(Math.cos(t)) * Math.cos(t) - Math.abs(Math.sin(t)) * Math.sin(t))
  5. })
  6.  
  7. const SIZE = 200
  8.  
  9. const c = document.body.appendChild(
  10.   Object.assign(document.createElement`canvas`,
  11.     { width: SIZE, height: SIZE }
  12.   )).getContext`2d`
  13.  
  14. c.fillStyle = 'black'
  15. c.fillRect(0, 0, SIZE, SIZE)
  16.  
  17. let t = 0
  18. setInterval(() => {
  19.   const { x, y } = rect(20, 20, 60, 70, t)
  20.   c.fillStyle = 'rgba(255, 0, 0, .1)'
  21.   c.fillRect(x, y, 10, 10)
  22.   t += .05
  23. }, 16)

Wanted to know how to do this for something back in 2015. Great math stackexchange answer here: http://math.stackexchange.com/questions/69099/equation-of-a-rectangle

Could be optimized but leaving as is to match:

x = p(|cos t|cos t + |sin t| sin t)
y = p(|cos t|cos t - |sin t| sin t)

One small change here is to add the width and height to the offset so that it draws from the upper left hand corner instead of the center…

// animation // graphics // javascript // math

Sort Local Git Branches by Date

  1. git for-each-ref --sort=-committerdate refs/heads/
  2.  
  3. # Or using git branch (since version 2.7.0)
  4. git branch --sort=-committerdate  # DESC
  5. git branch --sort=committerdate  # ASC

From this stackoverflow post: https://stackoverflow.com/a/5188364/502848

The above is very useful (who knows maybe SourceTree can do it too).

// git
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