JSベースの配列小練習(学習)

JSベースの配列小練習
注意:type

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        //var name = "  ,  ,  ";

    //1.  Array     
   /* var arr1 = new Array();//   
    var arr2 = new Array(20);//  20   
    var arr3 = new Array("     ","melt lilith",10);
    console.log(arr1);
    console.log(arr2);
    console.log(arr3);*/
    //2.       
    var arr4 = [];
    var arr5 = [30];
    console.log(arr4);
    console.log(arr5);
	
    
        var person = ["  ", " ", "23"];
    console.log(person);

    //        
    var number = [10, 1, 19, 22, 73];
    for(var i=0; i < number.length; i++){
        var item = number[i];
        if(item % 2 === 0){
            console.log(item);
        }
    }
	
    
        //            ，      

    //1.    
    var numArr = [1, 99, 88, -100, 77, 888];
    var maxValue = numArr[0], minValue = numArr[0];
    var maxIndex = 0,minIndex = 0;//         

    //2.    
    for(var i=1; i< numArr.length; i++){
        //                  
        if (numArr[i] > maxValue){
            //          ,     
            maxValue = numArr[i];
            maxIndex = i;
        }
        if (numArr[i] < minValue){
            minValue = numArr[i];
            minIndex = i;
        }
    }
    console.log(maxValue);
    console.log(maxIndex);
    console.log(minValue);
    console.log(minIndex);
	
    
        //      0    ，  0        
    var arr = ["   ", 18, 0, " ", 0, 8008208820];
    var newArr = [];
    for(var i=0; i< arr.length; i++){
        if(arr[i] !==0){
            newArr[newArr.length] = arr[i];
        }
    }
    console.log(newArr);
	
    
        // join(separator)
    var arr = ["  ",20,"   "];
    console.log(arr.join("|"));
	
    
        //push() pop()
    var arr = ["  ","    ","  "];
    var count = arr.push("   ","    ");
    console.log(count);
    console.log(arr);

    var item = arr.pop();
    console.log(item);
    console.log(arr);
	
    
        //shift()        ，         ，         undefined
    //unshift()            ，        
    var arr = ["  ","  ","  "];
    console.log(arr.shift());
    console.log(arr.shift());
    console.log(arr);
    var count = arr.unshift("   ","   ");
    console.log(count);
    console.log(arr);
	
    
        var arr = ["  ","  ","  "];
    arr.reverse();
    console.log(arr);//     
	
    
        //concat()           ，      copy       ，              copy      ，          ，    concat()          ，              
    var arr = [1, 3, 5, 7, 9];
    var copyArr = arr.concat(11, "   ");
    console.log(arr);
    console.log(copyArr);
    arr.push([11,17]);
    console.log(arr);
	
    
        //indexOf() lastIndexOf                                 -1
        //                 ，        
        //indexOf()       :       (   )           。  。            
        //lastIndexOf()       ：      (   )           。  ,            。
        var arr = [2, 4, 6, 8, 8, 6, 4, 2];
        console.log(arr.indexOf(4, 2));
        console.log(arr.lastIndexOf(4, 6));
        console.log(arr.indexOf("4")); //  -1