JavaScript Array Deduplication Scheme
- 2021-11-23 22:27:00
- OfStack
Directory method 1: set: not a data type, but a data structure; Member only 1 Method 2: Object attribute name cannot be duplicated Method 3: indexOf Method 4: sort Method 5: includes: Include; If the array contains that 1 item, return true;; Does not include returning false; Method 6: hasOwnProperty: Check whether the attribute name is a private attribute of the object; Returns 1 Boolean value; Method 7: filter+indexOf Method 8: splice Method 9: Recursive Method 10: Map: Using the characteristics of Map data structure; Method 101: reduce Method 102: Similar to set of Method 1, the residual operator is used...
There are several other ways to work with arrays
- includes
Method is used to determine whether an array contains a specified value, returning true if it does, or false if not.
- find
Returns the 1 item found the first time
- some
Returns 1 Boolean value as long as 1 is
true
, return
true
- every
Returns a Boolean value that requires true for every item to return true
- filter
Returns 1 new filtered array; If true is returned, it will stay, and false will be filtered out
- reduce
Convergence
Let's get down to business ~ (I hope it can help you ~ This site is a bit skinny!! Ha ha ha ha ha)
Method 1: set: It is not a data type, but a data structure; Member only 1
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let s = new Set(ary);
// Array.from : Will set The data structure is converted into a real array;
return Array.from(s)
}
unique(arr);
Method 2: Object property names cannot be duplicate
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let obj = {};
for(let i=0;i<ary.length;i++){
let cur = ary[i];
if(obj[cur]){
//ary.splice(i,1);// Causes the array to collapse
ary[i]=ary[ary.length-1];
ary.length--;// Delete the last 1 Items
i--;
continue;
}
obj[cur]=cur;// To obj Add key-value pairs; The property name and property value are 1 Like
}
}
unique(arr);
Method 3: indexOf
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let newAry = [];
for(let i=0;i<ary.length;i++){
let cur = ary[i];
if(newAry.indexOf(cur)===-1){
newAry.push(cur);
}
}
return newAry;
}
unique(arr)
Method 4: sort
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let a = ary.sort(function (a,b) {
return a-b;
});
for(let i=0;i<a.length;i++){
if(a[i]===a[i+1]){
a.splice(i+1,1);
i--;
}
}
return a;
}
unique(arr)
Method 5: includes: Include; If the array contains that 1 item, return true;; Does not include returning false;
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let newAry = [];
let len = ary.length;
for(let i=0;i<len;i++){
let cur = ary[i];
if(!newAry.includes(cur)){
newAry.push(cur);
}
}
return newAry;
}
console.log(unique(arr));
Method 6: hasOwnProperty: Check whether the attribute name is a private attribute of the object; Returns 1 Boolean value;
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let obj = {};
return ary.filter(function (item,index,a) {
// item : Array per 1 Members
// index: Index corresponding to member
// a : Entire array
// hasOwnProperty To verify whether the attribute of has appeared;
return obj.hasOwnProperty(typeof item+item)?false:obj[typeof item+item]=true;
if(obj.hasOwnProperty(typeof item+item)){
return false
}else{
obj[typeof item+item]=true;
return true;
}
})
}
console.log(unique(arr))
Method 7: filter+indexOf
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
return ary.filter(function (item,index,a) {
return ary.indexOf(item)===index;
})
}
console.log(unique(arr));
Method 8: splice
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
for(let i=0;i<ary.length;i++){
for(j=i+1;j<ary.length;j++){
if(ary[i]===ary[j]){
ary.splice(j,1);
j--;
}
}
}
return ary;
}
unique(arr);
Method 9: Recursion
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let len= ary.length;
ary = ary.sort(function (a,b) {
return a-b;
});
function loop(index) {
if(index>=1){
if(ary[index]===ary[index-1]){
ary.splice(index,1);
}
loop(index-1)
}
}
loop(len-1);
return ary;
}
console.log(unique(arr));
Method 10: Map: Using the characteristics of Map data structure to store values;
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let newAry =[];
let map = new Map();
for(let i=0;i<ary.length;i++){
if(!map.has(ary[i])){
map.set(ary[i],true);
newAry.push(ary[i]);
}
}
}
unique(arr);
Method 101: reduce
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let obj = {};
for(let i=0;i<ary.length;i++){
let cur = ary[i];
if(obj[cur]){
//ary.splice(i,1);// Causes the array to collapse
ary[i]=ary[ary.length-1];
ary.length--;// Delete the last 1 Items
i--;
continue;
}
obj[cur]=cur;// To obj Add key-value pairs; The property name and property value are 1 Like
}
}
unique(arr);
Method 102: Similar to set in Method 1, the residual operator is used...
let arr = [12,1,12,3,1,88,66,9,66];
function unique(ary) {
let obj = {};
for(let i=0;i<ary.length;i++){
let cur = ary[i];
if(obj[cur]){
//ary.splice(i,1);// Causes the array to collapse
ary[i]=ary[ary.length-1];
ary.length--;// Delete the last 1 Items
i--;
continue;
}
obj[cur]=cur;// To obj Add key-value pairs; The property name and property value are 1 Like
}
}
unique(arr);