JS数组去重

indexOf实现

var array = [1, 1, '1'];
function unique(array) {
var res = [];
for (var i = 0, len = array.length; i < len; i++) {
  var current = array[i];
  if (res.indexOf(current) === -1) {
      res.push(current)
  }
}
return res;
} 
console.log(unique(array));

排序后去重

var array = [1, 1, '1'];
function unique(array) {
var res = [];
var sortedArray = array.concat().sort();
var seen;
for (var i = 0, len = sortedArray.length; i < len; i++) {
  // 如果是第一个元素或者相邻的元素不相同
  if (!i || seen !== sortedArray[i]) {
      res.push(sortedArray[i])
  }
  seen = sortedArray[i];
}
return res;
}

filter实现

var array = [1, 2, 1, 1, '1'];
function unique(array) {
var res = array.filter(function(item, index, array){
  return array.indexOf(item) === index;
})
return res;
}
console.log(unique(array));

排序去重

var array = [1, 2, 1, 1, '1'];
function unique(array) {
return array.concat().sort().filter(function(item, index, array){
  return !index || item !== array[index - 1]
})
}
console.log(unique(array))

Object键值对

var array = [{value: 1}, {value: 1}, {value: 2}];
function unique(array) {
var obj = {};
return array.filter(function(item, index, array){
  console.log(typeof item + JSON.stringify(item))
  return obj.hasOwnProperty(typeof item + JSON.stringify(item)) ? false : (obj[typeof item+JSON.stringify(item)] = true)
})
}
console.log(unique(array)); // [{value: 1}, {value: 2}]

ES6 Set实现

var unique = (a) => [...new Set(a)]