数组去重

arrayUnique.js

Array.prototype.unique = function() { //查找索引 indexOf
  var ret = []
  for (var i = 0; i < this.length; i++) {
    if (ret.indexOf(this[i]) == -1) {
      ret.push(this[i])
    }
  }
  return ret;
}
Array.prototype.unique = function() { //借用对象
  var ret = [], obj = {};
  for (var i = 0; i < this.length; i++) {
    if (!obj[this[i]]) {
      obj[this[i]] = true;
      ret.push(this[i])
    }
  }
  return ret;
}

Array.prototype.unique = function() { //sort->filter
  return this.sort((a,b) => a - b ).filter((e,i,a) => a[i] !== a[i - 1]);
}

Array.prototype.unique = function() { //借用set
  return [...new Set(this)];
}