如何计算项目在数组中的次数-Howtocountnumberoftimesanitemisinanarray

heres an algorithm :

下面是一个算法:

Use an object to store the user no. and the count. like :

使用对象存储用户号。和伯爵。喜欢 :

{"222":"3","444":"1"}

this means 222 has visited 3 times and 444 visited once. now every time a user checks in:

这意味着222次访问过3次,444次访问过一次。现在每次用户签入时:

1. see if the key with the user's number exists, if yes increment the count. if no, add a new entry with count = 1.

查看是否存在具有用户编号的密钥,如果是则增加计数。如果不是,请添加count = 1的新条目。

2. check if the number is 5, if yes get free coffee and reset count to zero. skip if no.

检查数字是否为5,如果是,则获取免费咖啡并重置计数为零。如果没有,请跳过

I would solve the problem by storing the visit count in a dictionary that maps each customer's ID to the number of times they have visited. The dictionary is initially empty. When you look up an ID in the dictionary for the first time, you'll get undefined, which tells you that you must initialize the value.

我会通过将访问计数存储在一个字典中来解决问题,该字典将每个客户的ID映射到他们访问过的次数。字典最初是空的。当您第一次在字典中查找ID时,您将获得未定义,这告诉您必须初始化该值。

The following demonstration has a couple of buttons that you can use to make Alice or Bob visit the shop. Click on the blue button at the bottom to start the demo.

以下演示有几个按钮,您可以使用这些按钮让Alice或Bob访问该商店。单击底部的蓝色按钮开始演示。

function message(s) {  // Simple output for a code snippet.
  document.getElementById('display').innerHTML += s + '
';
}

var coffeeCount = {};  // Stores the number of visits by each customer.

function customerVisit(id) {  // Called when a customer visits.
  if (coffeeCount[id] === undefined) {  // Check for first visit.
    coffeeCount[id] = 0;                // Initialize the visit count.
  } 
  var count = ++coffeeCount[id];        // Increment the visit count.
  message(id+': '+count+' visit'+(count == 1 ? '' : 's'));
  if (count % 5 == 0) {                 // Check for free coffee.
    message('→ Free coffee for customer '+id+'!');
  } 
}

Alice

Bob

Try including utilization of input elements; set visits count as value of property id, info at object list; call test with value of input element : id ; or at prompt : info . At five visits , display coffee , reset value of id to 0.

尝试包括输入元素的使用;将访问次数设置为属性id的值,对象列表中的信息;使用input元素的值调用test:id;或者在提示时:info。在五次访问时,显示咖啡,将id的值重置为0。

var list = {
  "111": 0,
  "222": 0,
  "333": 0,
  "444": 0,
  "555": 0,
  "666": 0
};

var test = function test(id) {
  coffee.innerHTML = "";
  var info;
  if (id.length > 0 && !/^(\s)/.test(id)) {
    if (list.hasOwnProperty(id)) {
      ++list[id];

    } else {
      list[id] = 1;
    }
    info = confirm("hi " + id + " this is your " + list[id] + " visit");
  } else {
    info = prompt("hi, please enter an id");
    if (!!info && !/^(\s)/.test(info) && list.hasOwnProperty(info)) {
      list[info] = 1;
      confirm("hi " + info + " this is your " + list[info] + " visit");
    } else {
      info = prompt("hi, please input a different id");
      if (!!info && !/^(\s)/.test(info) && !list.hasOwnProperty(info)) {
        list[info] = 1;
        confirm("hi " + info + " this is your " + list[info] + " visit");
      }
    };
    alert("please try a different id")
  };

  for (var id in list) {
    if (list[id] === 5) {
      alert("hi " + id + ", thanks for visting " + list[id] + " times");
      coffee.innerText = "☕";
      list[id] = 0;
      break;
    }
  };

  console.log(list);

};

var inputs = document.querySelectorAll("input");
var coffee = document.getElementById("coffee");
coffee.style.fOntSize= "5em";

inputs[1].Onclick= function(e) {
  test(inputs[0].value)
};

n is number of costumer

n是客户的数量

Initially array is [0,0,0,.....n times]

最初的数组是[0,0,0,..... n次]

All values are 0 because no costumer has visited the shop.

所有值均为0,因为没有客户访问过该商店。

For n=5 array would look like

对于n = 5阵列看起来像

var a=[0,0,0,0,0];

1)To solve this problem in array.

1)在阵列中解决这个问题。

2)Suppose we have array of size n.

2)假设我们有大小为n的数组。

3)then index of the array will be 0...n-1

3)然后数组的索引将是0 ... n-1

4)So we can map id of costumer to the index.

4)因此我们可以将客户的id映射到索引。

5)And value will keep count of the number of visit for the index.

5)并且值将保留索引的访问次数。

6)a[5]=11; here 5 is index and 11 is value

6)[5] = 11;这里5是索引,11是值

7)For our problem if customer with id i we increment a[i]=a[i]+1 if he visits .

7)对于我们的问题,如果客户有身份我,如果他访问,我们增加[i] = a [i] +1。

8) Then we can check

8)然后我们可以检查

if(a[i]+1 === 5) {
   console.log("Custumer "+ i + " get a free coffee");
   a[i]=0;
}
else {
   a[i]=a[i]+1;
}

I've decided to just try again from the start since I'm a bit more awake now and go over building this step by step. i've looked at some of the answers and there seems to be manyt ways one could go about this. I'm trying to do this using what I've learned so far. I've learned about variables, basic functions, objects, arrays, 'this' and the push method. I know for, while, do while, for in loops, though the for loop is the one I understand the best.

我决定从一开始就再试一次,因为我现在更加清醒,然后逐步重建。我已经看了一些答案,似乎有很多方法可以解决这个问题。我正试图用我迄今学到的东西来做这件事。我已经了解了变量,基本函数,对象,数组,'this'和push方法。我知道,虽然,for while,for循环,虽然for循环是我理解最好的。

Here is my new approach to building this, I know it's unnecessarily long but I want to be able to get a basic understanding of how to piece the different things I've learned together in a very simple way. This is more about learning how to go about building simple programs. Then I would proceed in fine-tuning the program to make it more concise and clever. If you could have a look and tell me how I would proceed with what I've got so far...

这是我建立这个的新方法,我知道这是不必要的长,但我希望能够基本了解如何以非常简单的方式拼凑我学到的不同的东西。这更多的是学习如何构建简单的程序。然后我将继续微调程序,使其更简洁,更聪明。如果你能看看并告诉我如何继续我到目前为止所做的事情......

Here is the code, Ideally I want to run a function when there's a new 'visitor' that asks for their name and number. Then create a new 'customer' object with the given name and number and push it to a 'visitors' array. once I've successfully figured that out I would use loops to check the array if the visitor is new or not, and update their number of visits everytime they come.

这是代码,理想情况下,当有一个新的“访问者”询问他们的姓名和号码时,我想运行一个函数。然后使用给定的名称和编号创建一个新的“客户”对象,并将其推送到“访问者”数组。一旦我成功地解决了这个问题,我会使用循环检查数组,如果访问者是新的,并在每次访问时更新他们的访问次数。

//array that will contain 'Customer' objects
var visitors = [john];

//Customer object
function Customer(name, phonenumber){
  this.name = name;
  this.phOnenumber= phonenumber;
//will eventually add a "visits" method logging number of visits

}

var john = new Customer("john smith", "333");

//visitor funtion that runs everytime there is a new visitor
var visitor = function(){

  //visitor does not have a set name or number yet
  var userNumber = "variable userNumber is currently equal to " + 0;
  var userName = "variable userName is currently set to " + undefined;
  console.log(userName, userNumber);

  //ask for visitor name and number
  var askNumber = prompt("type your number");
  var askName = prompt("what is your name?");

  //store user name and number in two variables
  var userNumber = "variable 'userNumber' is now equal to " + askNumber; 
  var userName = "variable userName is now set to " + askName;

  //print out the new variables 
  console.log(userNumber);
  console.log(userName);

  //print who the phone number belongs to, this lets me see that the above code worked correctly
  var userNumber = askNumber;
  var userName = askName;
  console.log("Phone number " + userNumber + " belongs to " + userName);

  //make new customer object with the given name and number
  var userNumber = new Customer();
  userNumber.name = askName;
  userNumber.phOnenumber= askNumber;

  console.log("properties of " + userNumber);  

};

the last bit returns "properties of [object, object]" why?

最后一位返回“[object,object]的属性”为什么?

I will give you a short function to check how many times a specific value is at the array:

我将给你一个简短的函数来检查特定值在数组中的次数:

function countHowManyTimesAValueIsOnArray(arr, valueToCheck){
    return  arr.filter(function(arrayValueToCompare){
        return arrayValueToCompare === valueToCheck;
    }).length
}

Attention for the use of '===' instead of '=='. This will compare the value considering its type. 222 will not be found as "222"

注意使用'==='而不是'=='。这将比较考虑其类型的值。 222将不会被发现为“222”

No need to complicate things here's an simple way, just add a count function that search how many times user has enter

这里不需要复杂的事情是一个简单的方法,只需添加一个计数函数来搜索用户输入的次数

 var list = ["111", "222", "333", "444", "555", "666"];
var test = function(input){
  var info = prompt("hi " + input + " what is your name?");
  var check=0;
    for(i=0; i