JavaScript several arrays remove duplicate values method recommend _javascript tips

An array to repeat is a common requirement, and we temporarily consider the same type of array to repeat. The main reason is to clear the thinking and consider the performance. The following methods, the basic online have, here is simply summed up.

Ideas:

1. Iterate over the array, compare, compare to the same delete the following
2. Iterate over the array, compare, compare to the same, skip the previous repeats, and add the new array
3. Take an array element into the new array, iterate through the remaining array elements, and compare the elements of the new array, if different, put the new array.
4. Traverse the array, take an element, as the object's property, to determine whether the property exists

1. Delete the following duplicates:

function Ov1 (arr) {
  //var a1= (New Date). GetTime ()) for
  (Var i=0;i<arr.length;i++) for
    (Var j=i+1;j< arr.length;j++)
      if (Arr[i]===arr[j]) {arr.splice (j,1); j--;}      
  Console.info (New Date). GetTime ()-a1) return        
  arr.sort (function (a,b) {return a-b});

2. This is the normal method, better understanding, if the same, jump out of the loop

function Ov2 (a) {
  //var a1= (New Date). GetTime ())
  var b = [], n = a.length, I, J;
  for (i = 0; i < n; i++) {for
    (j = i + 1; j < N; j +)
      if (a[i] = = A[j]) {j=false;break;}
    if (j) B.push (A[i]);
    }
  Console.info (New Date). GetTime ()-a1) return  
  b.sort (function (a,b) {return a-b});
 

3. It took me a long time to understand where the J Loop went on, but the I value has changed. is equal to a new I loop:

function Ov3 (a) {
  //var a1= (New Date). GetTime ())
  var b = [], n = a.length, I, J;
  for (i = 0; i < n; i++) {for
    (j = i + 1; j < N; j +)
    if (a[i] = = A[j]) j=++i
  B.push (a[i));
  Console.info (New Date). GetTime ()-a1) return  
  b.sort (function (a,b) {return a-b});
   

4. Ensure that the new array is unique

function ov4 (AR) {
//var a1= (New Date). GetTime ())
  var m=[],f;
  for (Var i=0;i<ar.length;i++) {
  f=true; 
  for (Var j=0;j<m.length;j++)
  if (Ar[i]===m[j]) {f=false;break;};
  if (f) m.push (Ar[i])}
//console.info ((New Date). GetTime ()-a1) return  
  m.sort (function (a,b) {return a-b});

5. Use Object properties

	function Ov5 (AR) {
	//  var a1= (new Date). GetTime ()
			var m,n=[],o= {};
			for (var i=0; (m= ar[i])!==undefined;i++)
			if (!o[m)) {N.push (m); o[m]=true;}  Console.info (New Date). GetTime ()-a1) return  
		n.sort (function (a,b) {return a-b});
		

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