一般的なJS配列の重量除去方法




	
		
		    
	
	
	
	
		let arr = [1, 2, 5, 4, 1, 3, 8, 2, 5];

		//ES6 set  
		//Set         ,     Set     。      ,           ,      。
		let newArr1 = Array.from(new Set(arr));		//   Array.from Set       
		console.log('newArr1',newArr1);

		//  sort()    ,                     。
		arr = arr.sort();
		let newArr2 = [];
		for (let i = 0; i < arr.length; i++) {
			if (arr[i] !== arr[i + 1]) {
				newArr2.push(arr[i])
			}
		}
		console.log('newArr2',newArr2)
		
		//    
		let newArr3 = arr;
		var len =newArr3.length;
		newArr3.sort(function(a,b){return a-b});
		function loop(index){
			if(index>=1){
				if(newArr3[index] === newArr3[index-1]){
					newArr3.splice(index,1)
				}
				loop(index - 1);  
			}
		}
		loop(len-1);
		console.log('newArr3',newArr3);
		
		//  for    ,        。    ,      
		let newArr4 = arr;
		for( let i=0;i<newArr4,length;i++){
			for(let j=i+1;j<newArr4.length;j++){
				if(newArr4[i] == newArr4[j]){
					newArr4.splice(j,1);
					j--;
				}
			}
		}
		console.log('newArr4',newArr4)
		
		//indexof         ,                  ,
		let newArr5 = [];
		for(let i=0;i<arr.length;i++){
			if(newArr5.indexOf(arr[i]) ===-1){
				newArr5.push(arr[i])
			}
		}
		console.log('newArr5',newArr5)