数组操作

@bluexiaowei

1. 数组去重

Array.prototype.unique1 = function(arr) {
  var
    i,
    length = this.length,
    mapArray = [],
    hash = {};
  for (i = 0; i < length; i += 1) {
    !hash[this[i]] && (
        hash[this[i]] = true,         
        mapArray.push(this[i])
    );
  }
  if(arr){
    for(i = 0, length = arr.length; i < length; i += 1) {
      !hash[arr[i]] && (
        hash[arr[i]] = true,
        mapArray.push(arr[i])
      );
    }
  }
  return mapArray;
};
Array.prototype.unique2 = function() {
  var 
    i,
    length = this.length,
    mapArray = [];
  this.sort();
  for (i = 0; i < length; i += 1){
    this[i] != this[i + 1] && mapArray.push(this[i]);
  }
  return mapArray;
}
Array.prototype.unique3 = function() {
  var
    i,
    length = this.length;
    mapArray = [];
  for (i = 0; i < length; i += 1){
    mapArray.indexOf(this[i]) == -1 && mapArray.push(this[i]);
  }
  return mapArray;
};
Array.prototype.unique4 = function() {
  var 
    i,
    length = this.length;
    mapArray = [this[0]];
  for (i = 1; i < length; i +=1) {
    this.indexOf(this[i]) == i && mapArray.push(this[i]);
  }
  return mapArray;
}

2. 数组去同留异 true、去异留同 false

function reserve(arr1, arr2, mode) {
  var
    i,
    length,
    key,
    mapArray = [],
    hash = {};
  for(i = 0, length = arr2.length; i < length; i += 1) {
    !hash[arr2[i]] && (
      hash[arr2[i]] = true,
      mapArray.push(arr2[i])
    );
  }
  arr2 = mapArray;
  mapArray = [];
  hash = {};
  for(i = 0, length = arr1.length; i < length; i += 1) {
    hash[arr1[i]] = true;
  }
  for(i = 0, length = arr2.length; i < length; i += 1) {
    if(mode) {
      hash[arr2[i]] && mapArray.push(arr2[i]);
    } else {
      hash[arr2[i]] ? delete hash[arr2[i]] : mapArray.push(arr2[i]);
      for(key in hash) {
        if(hash.hasOwnProperty(key)) {
          mapArray.push(key);
        }
      }
    }
  }
  return mapArray;
}

3. 数组排序

/*升序*/
Array.sort();
/*降序*/
array = array.sort( function( a, b ) { return b - a } );
/*乱序*/
array = array.sort( function() { return Math.random() - 0.5 } );
/* true 升序  false 降序*/
Array.prototype.bubble = function(mode) {
  var
    i,
    j,
    yes,
    value,
    length = this.length;
  for(i = 0; ;i += 1) {
    yes = true;
    for(j = 0; j < length; j += 1) {
        if (mode){
            this[j] > this[j + 1] && (
                value = this[j + 1],
                this[j + 1] = this[j],
                this[j] = value,
                yes = false
            );
        } else {
            this[j] < this[j + 1] && (
                value = this[j + 1],
                this[j + 1] = this[j],
                this[j] = value,
                yes = false
            ); 
        }
    }
    if(yes) return this;
  }
};
/*乱序*/
Array.prototype.shuffle = function() {
  var
    j,
    x,
    i = this.length;
  for(; i;) {
    j = parseInt(Math.random() * i);
    x = this[--i];
    this[i] = this[j];
    this[j] = x;
  };
  return this;
};

4. 数组合并

/*内置方法*/
var arr = arr1.concat(arr2);
/*优化*/
var arr = Array.prototype.push.call(arr1,arr2);
/*或者*/
arr1.push.call(arr1,arr2);

 

5. 数组截断

/*减小数组长度*/
var 
  arr = [1, 2, 3, 4, 5, 6, 7];
  console.log(arr);[1, 2, 3, 4, 5, 6, 7];
  arr.length = 3;
  console.log(arr);//[1, 2, 3]

 

6. 数组截取

var arr, array = [ 1, 2, 3, 4, 5, 6 ];
arr = array.slice();
console.log( arr ); //[ 1, 2, 3, 4, 5, 6 ]
arr = array.slice( 2, 5 );
console.log( arr ); //[ 3, 4, 5 ]
arr = array.slice( -2, 5 );
console.log( arr ); //[ 5 ]
arr = array.slice( -2, -1 );
console.log( arr ); //[  ]
arr = array.slice( -3 );
console.log( arr ); //[ 4, 5, 6 ]

7. 深度克隆

javscript 中数组类型分两种，原始类型、对象类型。都可以用浅克隆。除了对象类型中的对象得用深度克隆。
function clone(object){
  var 
    key,
    newObj,
    obj = Object.prototype.toString.call(object).slice(8,-1);
  if(obj !== 'Object'){
    return newObj = object;
  } else if (window.JSON) {
    newObj = JSON.stringify(object);
    newObj = JSON.parse(newObj);
    return newObj;
  } else {
    for(key in object){
      newObj[key] = object[key];
    }
    return newObj;
  }
}