Share 11 useful JavaScript tips

In this article today, I want to share with you 11 useful JavaScript tips that will greatly improve your work efficiency.

1. Two ways to generate random colors

1).Generate RandomHexColor

const generateRandomHexColor = () => {
  return `#${Math.floor(Math.random() * 0xffffff).toString(16).padStart(6, '0')}`
}

generateRandomHexColor() // #a8277c
generateRandomHexColor() // #09c20c
generateRandomHexColor() // #dbc319

2).Generate random RGBA

const generateRandomRGBA = () => {
  const r = Math.floor(Math.random() * 256)
  const g = Math.floor(Math.random() * 256)
  const b = Math.floor(Math.random() * 256)
  const a = Math.random().toFixed(2)

return `rgba(${[ r, g, b, a ].join(',')})`
}
generateRandomRGBA() // rgba(242,183,70,0.21)
generateRandomRGBA() // rgba(65,171,97,0.72)
generateRandomRGBA() // rgba(241,74,149,0.33)

2. Two ways to copy content to the clipboard

Way 1

const copyToClipboard = (text) => navigator.clipboard && navigator.clipboard.writeText && navigator.clipboard.writeText(text)

copyToClipboard('hello medium')

Way 2

const copyToClipboard = (content) => {
  const textarea = document.createElement("textarea")


  textarea.value = content
  document.body.appendChild(textarea)
  textarea.select()
  document.execCommand("Copy")
  textarea.remove()
}

copyToClipboard('hello medium')

3. Get the query parameters in the URL

const parseQuery = (name) => {
  return new URL(window.location.href).searchParams.get(name)
}

// https://medium.com?name=fatfish&age=100
parseQuery('name') // fatfish
parseQuery('age') // 100
parseQuery('sex') // null

4.Please wait for a while

const timeout = (timeout) => new Promise((rs) => setTimeout(rs, timeout))

5. Scramble the array

const shuffle = (array) => array.sort(() => 0.5 - Math.random())

shuffle([ 1, -1, 2, 3, 0, -4 ]) // [2, -1, -4, 1, 3, 0]
shuffle([ 1, -1, 2, 3, 0, -4 ]) // [3, 2, -1, -4, 0, 1]

6. Deep copy an object

How to deep copy an object? Using StructuredClone makes it very easy.

const obj = {
  name: 'fatfish',
  node: {
    name: 'medium',
    node: {
      name: 'blog'
    }
  }
}

const cloneObj = structuredClone(obj)
cloneObj.name = '1111'
cloneObj.node.name = '22222'
console.log(cloneObj)
/*
{
    "name": "1111",
    "node": {
        "name": "22222",
        "node": {
            "name": "blog"
        }
    }
}
*/
console.log(obj)
/*
{
    "name": "fatfish",
    "node": {
        "name": "medium",
        "node": {
            "name": "blog"
        }
    }
}
*/

7. Make sure the element is within the visible area

Some time ago, I encountered a very troublesome need at work. Thanks to IntersectionObserver, I could easily detect whether an element was within the visible area.

const isElInViewport = (el) => {
  return new Promise(function(resolve) {
    const observer = new IntersectionObserver((entries) => {
      entries.forEach((entry) => {
        if (entry.target === el) {
          resolve(entry.isIntersecting)
        }
      })
    })

observer.observe(el)
  })
}
const inView = await isElInViewport(document.body)
console.log(inView) // true

8. Get the currently selected text

Many translation websites have this feature where you can select text and translate it into another country's language.

const getSelectedContent = () => window.getSelection().toString()

9. Get all browser cookies

Very convenient to help us obtain cookie information in the browser

const getAllCookies = () => {
  return document.cookie.split(";").reduce(function(cookieObj, cookie) {
    const cookieParts = cookie.split("=")
    cookieObj[cookieParts[0].trim()] = cookieParts[1].trim()
    return cookieObj
  }, {})
}

getAllCookies() 
/*
{
    "_ga": "GA1.2.496117981.1644504126",
    "lightstep_guid/medium-web": "bca615c0c0287eaa",
    "tz": "-480",
    "nonce": "uNIhvQRF",
    "OUTFOX_SEARCH_USER_ID_NCOO": "989240404.2375598",
    "sz": "2560",
    "pr": "1",
    "_dd_s": "rum"
}
*/

10. Delete the cookie with the specified name

My friends, we can only delete cookies without HttpOnly flag.

const clearCookie = (name) => {
  document.cookie = name + "=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=/;";
}

clearCookie('_ga') // _ga is removed from the cookie

11. Convert multi-dimensional array to one-dimensional array

Although, we convert a multi-dimensional array into a one-dimensional array through a recursive function, there is a very simple way to solve this problem.

const flatten = (array) => {
  return array.reduce((result, it) => {
    return result.concat(Array.isArray(it) ? flatten(it) : it)
  }, [])
}

const arr = [
  1,
  [
    2,
    [
      3,
      [
        4,
        [
          5,
          [
            6
          ]
        ]
      ]
    ]
  ]
]
console.log(flatten(arr)) // [1, 2, 3, 4, 5, 6]

The secret is to use the flattening method of arrays.

const arr = [
  1,
  [
    2,
    [
      3,
      [
        4,
        [
          5,
          [
            6
          ]
        ]
      ]
    ]
  ]
]
console.log(arr.flat(Infinity)) // [1, 2, 3, 4, 5, 6]

Summarize

The above are 11 useful tips that I want to share with you today. I hope they will be helpful to you.

Thanks for reading until the end, and happy programming!

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