Detailed Discussion on Several Methods of Reduplication Removal of JavaScript Array

Directory 1. Set deduplication 2. Double for cyclic deduplication 3. Using indexOf deduplication 4. Using icludes deduplication 5. filter 6. Map summary

1. Set Weight Removal

 function funSet(arr){
   return Array.from(new Set(arr));
 }

2. Double for cycle deduplication

function funFor(arr){
  for(let i=0,len=arr.length;i<len;i++){
    for(let j=i+1,len=arr.length;j<len;j++){
      if(arr[i]===arr[j]){
        arr.splice(j,1);
        len--;
        j--;
      }
    }
  }
  return arr;
}

3. Use indexOf to remove weight

function funIndex(arr){
  let newArr=[];
  for(let i=0;i<arr.length;i++){
    if(newArr.indexOf(arr[i])===-1){
      newArr.push(arr[i])
    }
  }
  return newArr;
}

4. Use icludes to remove weight

function funInclude(arr){
  let newArr=[];
  for(let i=0;i<arr.length;i++){
    if(!newArr.includes(arr[i])){
      newArr.push(arr[i])
    }
  }
  return newArr;
}

5. filter

function funFilter(arr){
  return arr.filter(function(item,index){
    return arr.indexOf(item,0)===index;
  })
}

6. Map

function funMap(arr){
  let map=new Map();
  let newArr=[];
  for(let i=0,len=arr.length;i<len;i++){
    if(map.has(arr[i])){
      map.set(arr[i],true);
    }else{
      map.set(arr[i],false);
      newArr.push(arr[i]);
    }
  }
  return newArr;
}

Summarize

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