1. Bubble Sort: pairwise comparison, large put back
for(var i=0;i<arr.length-1;i++){
for(var j=0;j<arr.length-1-i;j++){
if(arr[j] > arr[j+1]){
var ls = arr[j]
arr[j] = arr[j+1]
arr[j+1] = ls;
2. Select the sort: take the first and all subsequent comparison, to get the smallest, in the first place
for (var I = 0; I <-arr.length. 1; I ++) {
// 2. the first interim a saved, assume that the first one is the minimum
var LS = ARR [I];
var lsIndex = I;
for (var = I + J. 1; J <arr.length; J ++) {
// begin 3. Comparative, to find the absolute minimum, just verify the hypothesis is correct
iF (LS> ARR [J]) {
LS = ARR [J];
lsIndex = J;
}
}
// 4. after the round, to find the absolute minimum , do exchange
ARR [lsIndex] = ARR [I];
ARR [I] = LS;
Deduplication Array
1. Each element of the array in order to make the comparison with other elements, find duplicate elements, delete
var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5,5,5,5];
console.log(arr); //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5, 5, 5, 5]
function noRepeat1(arr) {
for(var i = 0; i < arr.length-1; i++){
for(var j = i+1; j < arr.length; j++){
if(arr[i]===arr[j]){
arr.splice(j,1);
j--;
}
}
}
return arr;
}
var arr2 = noRepeat1(arr);
console.log(arr2); //[1, 23, 3, 5, 6, 7, 9, 8]
2. by the indexOf () method of determining a position index of the first occurrence of this element circulating in the array index is equal
var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5,5,5];
console.log(arr); //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5, 5, 5]
function noRepeat2(arr) {
for (var i = 0; i < arr.length; i++) {
if (arr.indexOf(arr[i]) != i) {
arr.splice(i,1);//删除数组元素后数组长度减1后面的元素前移
i--;//数组下标回退
}
}
return arr;
}
var newArr = noRepeat2(arr);
console.log(newArr); //[1, 23, 3, 5, 6, 7, 9, 8]
3. The method of using the filter array
var arr = ['apple','banana','pear','apple','orange','orange'];
console.log(arr) //["apple", "banana", "pear", "apple", "orange", "orange"]
var newArr = arr.filter(function(value,index,self){
return self.indexOf(value) === index;
});
console.log(newArr); //["apple", "banana", "pear", "orange"]
4. With the new array is determined by the current element indexOf square array index if the cycle is equal to the index added to the new array
var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5,5,5];
console.log(arr) //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5, 5, 5]
function noRepeat4(arr) {
var ret = [];
for (var i = 0; i < arr.length; i++) {
if (arr.indexOf(arr[i]) == i) {
ret.push(arr[i]);
}
}
return ret;
}
var arr2 = noRepeat4(arr);
console.log(arr2); //[1, 23, 3, 5, 6, 7, 9, 8]
The use of space to record new objects already stored in the array element through
var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5];
console.log(arr) //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5]
var obj={};
var newArr=[];
for(var i=0;i<arr.length;i++){
if(!obj[arr[i]]){
obj[arr[i]]=true;
newArr.push(arr[i]);
}
}
console.log(newArr); //[1, 23, 3, 5, 6, 7, 9, 8]
6. With the new array, determines whether or not the new element if there is no element of this array is added to the presence of the new array
var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5];
console.log(arr); //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5]
function noRepeat6(arr){
var newArr = [];
for(var i = 0; i < arr.length; i++){
if(newArr.indexOf(arr[i]) == -1){
newArr.push(arr[i]);
}
}
return newArr;
}
var arr2 = noRepeat6(arr);
console.log(arr2); //[1, 23, 3, 5, 6, 7, 9, 8]
7. With the new array, determines whether or not the presence of the element does not exist, if this element is added into a new array (the same length but the original array is sorted in order of character string) in the new array
var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5];
console.log(arr); //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5]
function noRepeat7(arr) {
var ret = [],
end;//临时变量用于对比重复元素
arr.sort();//将数重新组排序
end = arr[0];
ret.push(arr[0]);
for (var i = 1; i < arr.length; i++) {
if (arr[i] != end) {//当前元素如果和临时元素不等则将此元素添加到新数组中
ret.push(arr[i]);
end = arr[i];
}
}
return ret;
}
var arr2 = noRepeat7(arr);
console.log(arr2); //[1, 23, 3, 5, 6, 7, 8, 9]
8. This method does not directly change the original array with the new array, and the array to be re-sorted
var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5];
console.log(arr); //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5]
function noRepeat8(arr) {
var end;//临时变量用于对比重复元素
arr.sort();//将数重新组排序
end = arr[0];
for (var i = 1; i < arr.length; i++) {
if (arr[i] == end) {//当前元素如果和临时元素相等则将此元素从数组中删除
arr.splice(i,1);
i--;
}else{
end = arr[i];
}
}
return arr;
}
var arr2 = noRepeat8(arr);
console.log(arr2); //[1, 23, 3, 5, 6, 7, 8, 9]
9. The double loop changes the original array
var arr = [1,1,2,2,3,3,4,4,5,5,4,3,1,2,6,6,6,6];
console.log(arr); //[1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 4, 3, 1, 2, 6, 6, 6, 6]
function noRepeat9(arr){
for (var i = 0; i < arr.length; i++) {
for (var j = 0; j < arr.length; j++) {
if (arr[i] == arr[j] && i != j) {//将后面重复的数删掉
arr.splice(j, 1);
}
}
}
return arr;
}
var arr2 = noRepeat9(arr);
console.log(arr2); //[1, 2, 3, 4, 5, 6]
10. With the new array
var arr = [1,1,2,2,3,3,4,4,5,5,4,3,2,1,1,1];
console.log(arr); //[1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 4, 3, 2, 1, 1, 1]
var newArr = [];
for (var i = 0; i < arr.length; i++) {
var repArr = [];//接收重复数据后面的下标
//内层循环找出有重复数据的下标
for (var j = i + 1; j < arr.length; j++) {
if (arr[i] == arr[j]) {
repArr.push(j);//找出后面重复数据的下标
}
}
//console.log(repArr);
if (repArr.length == 0) {//若重复数组没有值说明其不是重复数据
newArr.push(arr[i]);
}
}
console.log(newArr); //[5, 4, 3, 2, 1]
11. With Set structure ES6 provided
var arr = [1,1,2,2,3,3,4,4,5,5,4,3,2,1,1,1];
console.log(arr); //[1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 4, 3, 2, 1, 1, 1]
function noRepeat11(arr){
var newArr = [];
var myset = new Set(arr);//利用了Set结构不能接收重复数据的特点
for(var val of myset){
newArr.push(val)
}
return newArr;
}
var arr2 = noRepeat11(arr)
console.log(arr2); //[1, 2, 3, 4, 5]