js常用数组方法

1.数组合并去重

function arrMergeDeduplication(arr1,arr2){
   var concatArray = arr1.concat(arr2); //合并数组
   var newArray = [];
   for(var i = 0; i < concatArray.length; i++){
       if(newArray.indexOf(concatArray[i]) == -1){
           newArray.push(concatArray[i])
       }  
   }
   return newArray;
}

2.数组排序

1.使用sort()方法排序
function arraySort(arr){
  var arr = arr;
  var compare = function(x,y){
      if(x>y){
        return -1;
      }else if(x<y){
        return 1;
      }else{
        return 0;
      }
  }
  //compare方法也可以简写为function(a,b){ return a-b }
  var newarr = arr.sort(compare);
  return newarr;
} 

2.冒泡排序
function bubbleSort(arr){
  var t;
  for(var i = 0; i < arr.length; i++){
     for(var j = i+1; j < arr.length; j++){
        if(arr[i]>arr[j]){
           t = arr[j];
           arr[j] = arr[i];
           arr[i] = t;
        }
     }
  }
  return arr;
}

3.数组筛选

var arr = [1,2,3,4,5];
var condition = function(x){
  if(x>2){
    return x;
  }
}
var newarr = arr.filter(condition);
console.log(newarr) //[3,4,5]

4.数组与字符串的转换

var arr = [1,2,3,4,5];
//转字符串
var arrString = arr.toString(); //"1,2,3,4,5"
var arrString = arr.join(','); //"1,2,3,4,5"
//转数组
var arr = arrString.split(','); //[1,2,3,4,5]

5.数组截取

  var arr = ['a', 'b', 'c'];
  
  arr.slice(0)         // ["a", "b", "c"]
  arr.slice(1)         // ["b", "c"]
  arr.slice(1, 2)     // ["b"]
  arr.slice(2, 6)     // ["c"]
  arr.slice()           // ["a", "b", "c"]    无参数返回原数组
  
  arr.slice(-2)          // ["b", "c"]    参数是负数，则表示倒数计算的位置
  arr.slice(-2, -1)     // ["b"]