15 JavaScript functions to bookmark

TNTWeb – The full name of Tencent News Zhongtai front-end team, partners in the group have practiced and accumulated experience in Web front-end, NodeJS development, UI design, mobile APP and other large front-end fields.

At present, the team mainly supports the front-end development of Tencent news business. Besides business development, some front-end infrastructure has been accumulated to enable business efficiency improvement and product innovation.

The team advocates open source construction, has a variety of technical masters, the team GitHub address: github.com/tnfe

The author of this article is CZ GitHub: github.com/xucz

When developing a JavaScript project, it’s common to use previously developed utility functions. Collecting these functions will save you a lot of development time when you need them. This article brings you 15 common utility functions that you can use to solve problems in an elegant way.

1. Reverse digital

const reverseNumber = n= >
  parseFloat(`${n}`.split(' ').reverse().join(' ')) * Math.sign(n);

reverseNumber(123); / / 321
reverseNumber(-200); / / - 2
reverseNumber(32.4); / / 4.23
reverseNumber(-32.4); // -4.23
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2. Gets the largest n number in the array

const maxFromArray = (array, number = 1) = > [...array]
  .sort((x, y) = > y -x).slice(0, number);

maxFromArray([2.1.4.3.5.6]); / / [6]
maxFromArray([2.1.4.3.6.6].2); / / [6, 6]
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3. Calculating factorial

const factorial = (number) = >
  number < 0
    ? (() = > {
      throw new TypeError('Type error');
    })()
    : number <= 1
    ? 1
    : number * factorial(number - 1);

factorial(4); / / 24
factorial(10); / / 3628800
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4. Check whether the current operating environment is a browser

const isBrowser = () = >! [typeof window.typeof document].includes('undefined');

isBrowser(); // false (Node)
isBrowser(); // true (browser)
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5. Check whether the current running environment is Node.js

const isNode = () = >
  typeofprocess ! = ='undefined'&&!!!!! process.versions && !! process.versions.node; isNode();// true (Node)
isNode(); // false (browser)
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6. Gets the parameters on the URL

const getURLParams = url= >
  (url.match(/([^?=&]+)(=([^&]*))/g) || []).reduce(
    (a, v) = > (
      (a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1)), a
    ),
    {}
  );

getURLParams('qq.com'); / / {}
getURLParams('https://xx.com?name=tntweb&age=20');
// {name: 'tntweb', age: '20'}
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7. rgb(x,x,x)Color representation format is converted to object format

const toRGBObject = rgbStr= > {
  const [red, green, blue] = rgbStr.match(/\d+/g).map(Number);
  return { red, green, blue };
};

toRGBObject('rgb(100, 150, 200)'); // {red: 100, green: 150, blue: 200}
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8. Escape strings for use in HTML

const escapeHTML = str= >
  str.replace(
    /[&<>'"]/g.tag= >
      ({
        '&': '& '.'<': '< '.'>': '> '."'": '& # 39; '.'"': '" '
      }[tag] || tag)
  );

escapeHTML('<a href="#">tntweb</a>'); 
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9. Unescapes HTML characters

const unescapeHTML = str= >
  str.replace(
    /& |< |> | & # 39; |" /g.tag= >
      ({
        '& ': '&'.'< ': '<'.'> ': '>'.'& # 39; ': "'".'" ': '"'
      }[tag] || tag)
  );

unescapeHTML('< a href=" #" > tntweb< /a> ');
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10. Generates a random integer in the specified range

const randomIntegerInRange = (min, max) = >
  Math.floor(Math.random() * (max - min + 1)) + min;

randomIntegerInRange(1.7); / / 1-7
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11. Convert the tilde path to an absolute path

const reversePath = str= >
  str.replace(($| / / ^ ~| \) /,`The ${require('os').homedir()}$1 `);

reversePath('~/web'); // '/Users/[userName]/web'
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12. Gets the current URL without any parameters or fragment identifiers

const getBaseURL = url= > url.replace(/ [? #]. * $/.' ');

getBaseURL('https://xx.com/index?name=tntweb&company=tencent');
// https://xx.com/index
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13. Returns the length of the string in bytes

const byteSize = str= > new Blob([str]).size;

byteSize('🚗'); / / 4
byteSize('Hello World'); / / 11
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14. Gets the elements of the array randomly

const randomly = arr= > arr[Math.floor(Math.random() * arr.length)];

randomly([1.3.5.7.9.11]);
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15. Check that the string is valid JSON

const isValidJSON = str= > {
  try {
    JSON.parse(str);
    return true;
  } catch (e) {
    return false; }}; isValidJSON('{"name":"tntweb","age":20}'); // true
isValidJSON('{"name":"tntweb",age:"20"}'); // false
isValidJSON(null); // true
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