js常用小技巧黒科技-javascript(js)commonly used skill

  1.234 | 0

  ~~1.234

  1.234 >> 0

  +'123'

  +new Date()

  ""+[1, 2 , 3, 3, [2, 3, 4]]

  var a=1;
  var b=2;
  [a, b] = [b, a];
  console.log(a, b);

  Math.max(...[1,2,3])
  Math.min(...[1,2,3])

  new Date(...[2018,6,4])

  method 1: 
  [...'string']
  
  method 2: 
  Array.from('string')

  let obj1 = {a:1, b:2};
  let obj2 = {b:3, c:4};

  {...obj1, ...obj2}
       
  Object.assign(obj1, obj2)

var url = new URL('http://localhost:8000/news?a=1&b=2&c=3');
var searchParams = url.searchParams;
for (let key of searchParams.keys()){
  console.log('====');
  console.log('key === ', key);
  console.log('value === ', searchParams.get(key))
}

  function preFixNum(num, length) {
    return (Array(length).join('0') + num).slice(-length);
  }

  [...new Set(arr.map(v => JSON.stringify(v)))].map(v => JSON.parse(v))

  var arr = [1,2,3,4,5];
  
  method 1: 
  var sum = eval(arr.join('+'));
  
  method 2: 
  var sum = arr.reduce((prev,cur) => prev + cur);

  let money = 11111;
  
  method 1: 
  money.toLocaleString('en-US');
  
  method 2: 
  Intl.NumberFormat().format(money);
  
  method 3: 
  String(money).replace(/\B(?=(\d{3})+(?!\d))/g, ',');

  isTrue && console.log(1);

  function RGBtoHEX(rgb){
    return ((1<<24) + (rgb.r<<16) + (rgb.g<<8) + rgb.b).toString(16).substr(1);
  }

const delay = ms => new Promise(resolve => setTimeout(resolve, ms))

  Array.from(new Array(10).keys());

  let a = '   '.link('https://github.com/TigerHee/shareJS');
  console.log('a === ', a)

     'tigerHee'        
  /(tigerHee)/

     'tigerHee'         
  /(?:tigerHee)/

    'tiger'   'tiger'    'Hee'
  /tiger(?=Hee)/

    'Hee'   'Hee'   'tiger'
  /(?<=tiger)Hee/

    'tiger'   'tiger'     'java'
  /tiger(?!java)/