Two methods for JavaScript array to go heavy recommend _javascript techniques

1, the array to weight;

The array type does not provide a way to repeat, if you want to kill the repeating elements of the array, you have to do it yourself:

Method One: Using IndexOf method;

var aa=[1,3,5,4,3,3,1,4]
function arr (arr) {
  var result=[] for
  (var i=0; i<arr.length; i++) {
    if ( Result.indexof (Arr[i]) ==-1) {
      result.push (Arr[i])
    }
  console.log
  (Result)}      
arr (aa)

Method Two:

function Unique (arr) {
  var result = [], isrepeated;
  for (var i = 0, len = arr.length i < len; i++) {
    isrepeated = false;
    for (var j = 0, Len = result.length J < Len; J + +) {
      if (arr[i] = Result[j]) {  
        isrepeated = true;
        break;
      }
    }
    if (!isrepeated) {
      result.push (arr[i]);
    }
  return result;
}

method Two, the overall idea is to move the elements of the array to another array, the process of handling to check whether there is duplication, if there is a direct throw away. It can be seen from nested loops that this method is extremely inefficient. We can use a Hashtable structure to record existing elements so that the inner loops can be avoided. Exactly, implementing Hashtable in JavaScript is extremely simple, as follows:

function Unique (arr) {
  var result = [], hash = {};
  for (var i = 0, elem; (Elem = arr[i])!= null; i++) {
    if (!hash[elem]) {
      result.push (elem);
      Hash[elem] = true;
    }
  }
  return result;
}

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