JS 메소드 컬렉션

new Array(10).fill(0).map(function(v,i){return (i)}).sort(function(v,i){return  0.5-Math.random()}).filter(function(v,i){return i < 3})

function getInt(num){
    var rounded;
    rounded = (0.5 + num) | 0;
    return rounded;
}
//~~ ， Math.floor() ， 。
// ， ， ； ， ； 0
~~false;     // => 0
~~true;      // => 1
~~1.9;       // => 1
~~-1.9;      // => -1

const isOdd = num => !!(num & 1)

//Array map filter ES6 
// 
if (!Array.prototype.map) {
  Array.prototype.map = function(callback, thisArg) {
    var T, A, k;
    if (this == null) {
      throw new TypeError(" this is null or not defined");
    }
    var O = Object(this);
    var len = O.length >>> 0;
    if (Object.prototype.toString.call(callback) != "[object Function]") {
      throw new TypeError(callback + " is not a function");
    }
    if (thisArg) {
      T = thisArg;
    }
    A = new Array(len);
    k = 0;
    while(k < len) {
      var kValue, mappedValue;
      if (k in O) {
        kValue = O[ k ];
        mappedValue = callback.call(T, kValue, k, O);
        A[ k ] = mappedValue;
      }
      k++;
    }
    return A;
  };
}

if (!Array.prototype.filter){
  Array.prototype.filter = function(fun /* , thisArg*/)
  {
    "use strict";
    if (this === void 0 || this === null)
      throw new TypeError();
    var t = Object(this);
    var len = t.length >>> 0;
    if (typeof fun !== "function")
      throw new TypeError();
    var res = [];
    var thisArg = arguments.length >= 2 ? arguments[1] : void 0;
    for (var i = 0; i < len; i++)
    {
      if (i in t)
      {
        var val = t[i];

        // NOTE: Technically this should Object.defineProperty at
        //       the next index, as push can be affected by
        //       properties on Object.prototype and Array.prototype.
        //       But that method's new, and collisions should be
        //       rare, so use the more-compatible alternative.
        if (fun.call(thisArg, val, i, t))
          res.push(val);
      }
    }
    return res;
  };
}