Four ways to de-weigh JS arrays

1. Iterate through the original array and the new array. New an array that holds the unique elements that have been traversed.

function Uniquearr (list) {

var newarr= [list[0]];

for (Var i=1;i<list.length;i++) {

var isrepeat = false;

for (Var j=0;j<newarr.length;j++) {

if (list[i] = = Newarr[j]) {

isrepeat= true;

Break

}

}

if (!isrepeat) {

Newarr.push (List[i]);

}

}

return NEWARR;

}

var arr=[' A ', ' B ', ' C ', ' A ', ' B '];

Uniquearr (arr); Output:["A", "B", "C"]

2, by first sorting, and then compared with the adjacent elements to the weight (after sorting the same element will be adjacent)

function Uniquearr (list) {

List.sort ();//Sort an array

var newarr= [];

for (Var i=1;i<list.length;i++) {

if (list[i]!=list[i+1]) Newarr.push (List[i]);

}

return NEWARR;

}

var arr=[' A ', ' B ', ' C ', ' A ', ' B '];

Uniquearr (arr); Output:["A", "B", "C"]

3, create a new object to store, and then iterate through the array, to determine whether the object exists this value (Obj[i])

function Uniquearr (list) {

var obj= {},newarr=[list[0]];

Obj[list[0]]=true;

for (Var i=1;i<list.length;i++) {

if (!obj[list[i]]) {

Obj[list[i]]=true;

Newarr.push (List[i]);

}

}

return NEWARR;

}

var arr=[' A ', ' B ', ' C ', ' A ', ' B '];

Uniquearr (arr); Output:["A", "B", "C"]

4, judge by IndexOf (create a new data to hold the unique element, traverse the original array to judge (Newarr.indexof (Oldarr[i]) ==-1))

function Uniquearr (list) {

var newarr=[list[0]];

for (Var i=1;i<list.length;i++) {

if (Newarr.indexof (List[i]) ==-1) {

Newarr.push (List[i]);

}

}

return NEWARR;

}

var arr=[' A ', ' B ', ' C ', ' A ', ' B '];

Uniquearr (arr); Output:["A", "B", "C"]

Four ways to de-weigh JS arrays