js, jq array operation

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1. Determine whether an array contains another array

1. filter combined with indexOf

提示：这里可以添加本文要记录的大概内容：

arr1 = [1,2,3]
arr2 = [1,3,2,4]
arr3 = arr1.filter(function(val){
    
    
    return arr2.indexOf(val)>-1
})
arr3 =  arr1.filter((val)=>{
    
    
    return arr2.indexOf(val)>-1
})
if(arr1.length === arr3.length){
    
    
    // true：包含
}

2. Determine whether two arrays have intersection

// 判断两个数组是否有交集
arr1 = [1,2,3]
arr2 = [1,3,2,4]
arr3 = _.intersection(arr1,arr2)
if(arr1.length === arr3.length){
    
    
    // true：包含
}

3. includes

let a = [1, 2, 3, 4, 5, 6, 7, 8];
let b = [1, 2];
let c = [3, 9];
function includes(arr1, arr2) {
    
    
  return arr2.every(val => arr1.includes(val));
}
console.log(includes(a, b));  //true
console.log(includes(a, c));  //false

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2. Delete an item in the array

Array.prototype.remove = function(val) {
    
    
    var index = this.indexOf(val);
    if (index > -1) {
    
    
        this.splice(index, 1);
    }
};
var emp = ['abs','dsf','sdf','fd']
emp.remove('fd');

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3. Get the maximum and minimum values ​​of the array

$(function() {
    
    
  //JS快速获取数组的最大值和最小值
  var a = [1, 2, 3, 5];
  document.write("最大值为：" + Math.max.apply(null, a) + "
  ");
  document.write("最小值为：" + Math.min.apply(null, a) + "
  ");
  //多维数组
  var a = [1, 2, 3, [5, 6],
    [1, 4, 8]
  ];

  var ta = a.join(",").split(","); //转化为一维数组
  document.write("Math.max最大值为：" + Math.max.apply(null, ta) + "
  ");
  document.write("Math.min最小值为：" + Math.min.apply(null, ta) + "
  ");
  $('#maxDiv').html(Math.max.apply(null, ta));
})

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4. Array splicing

1. Use a for loop

var arr = ['tom', 'jerry'];
var arr2 = [1, 2];
for(var i=0; i<arr2.length; i++){
    
    
     arr.push(arr2[i])
}
console.log(arr); // ['tom', 'jerry', 1, 2]

2. concat()

注意concat()生成一个新数组

var arr = ['tom', 'jerry'];
var arr2 = [1, 2];
var newArr = arr.concat(arr2);
console.log(newArr); // ["tom", "jerry", 1, 2]

3. Use apply to hijack the push method of the array

推荐，apply具体使用方法参考MDN

var arr = ['tom', 'jerry'];
var arr2 = [1, 2];
arr.push.apply(arr, arr2);
console.log(arr) // ["tom", "jerry", 1, 2]

4. Use the 'dot syntax' spread operator in es6 (recommended)

var arr = ['tom', 'jerry'];
var arr2 = [1, 2];
arr.push(...arr2);
console.log(arr) // ["tom", "jerry", 1, 2]

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5. Get the number of each element in the array

1. for loop

var arr = [1,2,1];
var map = {
    
    };
for(var i = 0; i < arr.length; i++){
    
    
	var ai = arr[i];
	if(!map[ai]){
    
    
		map[ai] = 1;
	}else{
    
    
		map[ai]++;
	}
}
console.log(map); //{1: 2, 2: 1}

2. reduce

function statisticalFieldNumber(arr) {
    
    
	return arr.reduce(function (prev, next) {
    
    
		prev[next] = (prev[next] + 1) || 1;
		return prev;
	}, {
    
    });
}
var arr = ["apple","orange","apple","orange","pear","orange","yellow"];
console.log(statisticalFieldNumber(arr));  //{apple: 2, orange: 3, pear: 1, yellow: 1}

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6. Get the last item of the array

1. pop()

var arr = new Array("js","JavaScript","jQuery"); 
var end = arr.pop() 
console.log(end);//jQuery 
console.log(arr);//["js", "JavaScript"]

2. length-1

var arr = new Array("js","JavaScript","jQuery"); 
var end = arr[arr.length-1] 
console.log(end);//jQuery

3. slice(-1)

var arr = new Array("js","JavaScript","jQuery"); 
var end = arr.slice(-1); 
console.log(end);//["jQuery"]

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Seven, array merge

data=[ 
    {
    
    name: "安置地上年度在职人员人均工资", firstLetter: "A"}, 
    {
    
    name: "八级年增资", firstLetter: "B"}, 
    {
    
    name: "八级生活补贴", firstLetter: "B"}
]
合并为
data=[
    {
    
    label: "A", name: ["安置地上年度在职人员人均工资"]},
    {
    
    label: "B",name: ["八级年增资","八级生活补贴"]}
]

// 处理获取到的数据
changeDataList (data) {
    
    
  var initArray = []
  data.forEach(item => {
    
    
    var param = {
    
    
      label: '',
      name: [],
    }
    param.label = item.firstLetter
    initArray.push(param)
  })
  var newInitArray = this.deteleObject(initArray) // 数组去重
  newInitArray.forEach(list => {
    
    
    data.forEach(item => {
    
    
      if (list.label === item.firstLetter) {
    
    
        list.name.push(item.name)
      }
    })
  })
  return newInitArray
},

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8. Array deduplication

1.deteleObject method

export function deteleObject(obj) {
    
    
  var uniques = [];
  var stringify = {
    
    };
  for (var i = 0; i < obj.length; i++) {
    
    
    var keys = Object.keys(obj[i]);
    keys.sort(function(a, b) {
    
    
      return (Number(a) - Number(b));
    });
    var str = '';
    for (var j = 0; j < keys.length; j++) {
    
    
      str += JSON.stringify(keys[j]);
      str += JSON.stringify(obj[i][keys[j]]);
    }
    if (!stringify.hasOwnProperty(str)) {
    
    
      uniques.push(obj[i]);
      stringify[str] = true;
    }
  }
  uniques = uniques;
  return uniques;
}

2. $.unique directly removes duplicates

var yearArray = new Array(2009, 2009, 2010, 2010, 2009, 2010);
$.unique(yearArray);
console.log(yearArray);//2009,2010

3. $.unique sorting deduplication

var yearArray = new Array(2009, 2009, 2010, 2010, 2009, 2010);  
$.unique(yearArray<strong>.sort()</strong>);  
alert(yearArray);//2009,2010  

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Nine, array split

test相同的合并

var a = [
  {
    
    name: '222', id: 1, test: '啊啊啊'},
  {
    
    name: '44123', id: 5, test: '啊啊啊'},
  {
    
    name: '54', id: 1, test: '笑嘻嘻'},
  {
    
    name: '45', id: 5, test: '啊啊啊'},
  {
    
    name: '431', id: 1, test: '水电费'},
  {
    
    name: '62', id: 4, test: '阿萨德'},
  {
    
    name: '222', id: 1, test: '啊啊啊'},
  {
    
    name: '54', id: 4, test: '的的撒'},
  {
    
    name: '76', id: 1, test: '爱迪生'},
];
let result = a.reduce(function (initArray, item, xindex, array) {
    
    
  //initArray 初始值 或者是上一次调用返回的值
  //item 数组中当前被处理的元素
  //xindex 当前元素的下标
  //array 被reduce的数组  即上面代码中的数组a
  let index = item.test;
  if (initArray[index]) {
    
    
    initArray[index].push(item)
  } else {
    
    
    initArray[index] = [item]
  }
  return initArray
}, []);
console.log(result)

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10. Sorting an array of objects

1. Ascending order

function compare(property) {
    
    
  return (firstobj, secondobj) => {
    
    
    const firstValue = firstobj[property];
    const secondValue = secondobj[property];
    return firstValue - secondValue ; //升序
  };
}

2. Descending

function compare(property) {
    
    
  return (firstobj, secondobj) => {
    
    
    const firstValue = firstobj[property];
    const secondValue = secondobj[property];
    return secondValue - firstValue; //降序
  };
}

3. use

let arr = [{
    
    id:1},{
    
    id:2}];
arr = arr.sort(compare("id"));

升序
dataList = dataList.sort(function (a, b) {
    
    
  return a.value - b.value
})
降序
dataList = dataList.sort(function (a, b) {
    
    
  return b.value - a.value
})

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11. jQuery clears the empty values ​​in the array

var aa = ['12', '34', '', '423', ' ']
console.log($.grep(aa, function (n) {
    
    
  return $.trim(n).length > 0
}))
var aaa = aa.filter(item => $.trim(item).length > 0)
console.log(aaa)

var aaa = [{
    
    name:'111'},{
    
    name:''}]
var aaa =aaa.filter(item => $.trim(item.name).length > 0)

var arr=[
  {
    
     name:'黄金', weight:'', number:'' },
  {
    
     name:'白银', weight:'', number:'' },
  {
    
     name:'翡翠', weight:'', number:''}
]
var filter_res = arr.filter(item => item.weight != '' && item.number != '')
console.log(filter_res.length > 0 ? '通过': '不通过')

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12. The obtained array contains ob : Observer

var data = [116.486409, 39.991489, __ob__: Observer]

var b = JSON.parse(JSON.stringify(data))
console.log(b) // [116.486409, 39.991489]

var data = {
    
    'value':116, 'value':39, __ob__: Observer}
var b = JSON.stringify(data)

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13. Determine whether the array contains a certain value

judgeFamily (value) {
    
    
  //是否包含该元素 0 4 5
  if ((value.indexOf(0) > -1) || (value.indexOf(4) > -1) || (value.indexOf(5) > -1)) {
    
    //则包含该元素 0 4 5 
    this.isSoldier = true
  } else {
    
    
    this.isSoldier = false
  }
  //是否包含该元素 1 2 3
  if ((value.indexOf(1) > -1) || (value.indexOf(2) > -1) || (value.indexOf(3) > -1)) {
    
    
    this.isFamilies = true
  } else {
    
    
    this.isFamilies = false
  }
},

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14. Determine whether the attributes of two arrays are the same

for (var i in Object.keys(data.data)) {
    
    
  for (var j in Object.keys(this.enterInfo)) {
    
    
    if (Object.keys(data.data)[i] === Object.keys(this.enterInfo)[j]) {
    
    
      this.enterInfo[Object.keys(this.enterInfo)[j]] = Object.values(data.data)[i]
    } else {
    
    
      // console.log(Object.keys(data.data)[i],Object.keys(this.enterInfo)[j])
    }
  }
}

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15. Delete the same object in two arrays

1. splice

let arr1 = [{
    
    id:'1',name:'json'},{
    
    id:'2',name:'book'} ] //选中数据
let arr2 = [{
    
    id:'1',name:'json',age:'15'},{
    
    id:'2',name:'book',age:'16'},{
    
    id:'3',name:'ani',age:'17'}] //所有数据
for (var i=0; i<arr2.length; i++) {
    
    
  for (var j=0; j<arr1.length; j++) {
    
    
    if (arr2[i].id == arr1[j].id) {
    
    
      arr2.splice(i, 1);
    }
  }
}

2. $.grep

// 已使用
this.opened.forEach((item)=>{
    
    
  nameArr.forEach((name)=>{
    
    
    if(item === name){
    
    
      console.log(item,name)
      // this.opened.splice($.inArray(item,this.opened), 1);
      this.opened = $.grep(this.opened, function(value) {
    
    
        return value != item;
      });
    }
  })
})

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Sixteen, JS depth judgment two array object fields are the same

1. Determine whether the object is of type Object

/**
* 判断此对象是否是Object类型
* @param {Object} obj
*/
function  isObject(obj){
    
    
  return Object.prototype.toString.call(obj)==='[object Object]';
};

2. Determine whether this type is an Array type

/**
* 判断此类型是否是Array类型
* @param {Array} arr
*/
function isArray(arr){
    
    
  return Object.prototype.toString.call(arr)==='[object Array]';
};

3. Deeply compare whether two objects are the same

/**
*  深度比较两个对象是否相同
* @param {Object} oldData
* @param {Object} newData
*/
function equalsObj(oldData,newData){
    
    
  // 类型为基本类型时,如果相同,则返回true
  if(oldData === newData) return true;
  if(isObject(oldData)&&isObject(newData)&&Object.keys(oldData).length === Object.keys(newData).length){
    
    
    // 类型为对象并且元素个数相同

    // 遍历所有对象中所有属性,判断元素是否相同
    for (const key in oldData) {
    
    
      if (oldData.hasOwnProperty(key)) {
    
    
        if(!equalsObj(oldData[key],newData[key]))
        // 对象中具有不相同属性 返回false
          return false;
      }
    }
  }else if(isArray(oldData)&&isArray(oldData)&&oldData.length===newData.length){
    
    
    // 类型为数组并且数组长度相同

    for (let i = 0,length=oldData.length; i <length; i++) {
    
    
      if(!equalsObj(oldData[i],newData[i]))
      // 如果数组元素中具有不相同元素,返回false
        return false;
    }
  }else{
    
    
    // 其它类型,均返回false
    return false;
  }

  // 走到这里,说明数组或者对象中所有元素都相同,返回true
  return true;
};


// 使用
　var oldArr = [{
    
    
     name: "张三",
     age: 11,
  },{
    
    
     name: '李四',
     age: 21,
  }];
  var newArr = [{
    
    
     name: "张三",
     age: 11
  },{
    
    
     name: '王五',
     age: 21,
 }];
 console.log(equalsObj(oldArr,newArr));// false

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