Question

我正在关注此Counting the occurrences of JavaScript array elements以查找数组中每个项目的出现位置。如果任何项目发生超过或等于3次，那么我必须显示警报以下是我尝试过的代码：

var countries = India , Australia , Bangladesh , India , India , New Zealand , New Zealand , Pakistan , Pakistan , West Indies;

var recipientsArray = countries.sort(); 

var reportRecipientsDuplicate = [];
for (var i = 0; i < recipientsArray.length; ++i) {
    if (!reportRecipientsDuplicate[recipientsArray[i]])
        reportRecipientsDuplicate[recipientsArray[i]] = 0;
    ++reportRecipientsDuplicate[recipientsArray[i]]
    }
}

如何检查是否有任何项目发生了3次以上？感谢

Answer 1

您可以使用reduce方法轻松解决此问题。 reduce方法通过应用提供的回调函数来创建新数组或对象。

reduce()方法对累加器应用函数数组中的每个元素（从左到右）将其减少为a 单一价值。

＆＃13;

var countries = ['India' , 'Australia' , 'Bangladesh' , 'India' , 'India' , 'New Zealand' , 'New Zealand' , 'Pakistan' , 'Pakistan' , 'West Indies'];
var statistics=countries.reduce(function(obj,elem){
    obj[elem]=obj[elem] || 0;
    obj[elem]++;
    return obj;
},{});
for(country in statistics){
  if(statistics[country]>=3)
    console.log(country);
}

＆＃13;

Answer 2

试试这段代码：

var countries = ["India" , "Australia" , "Bangladesh" , "India" , "India" , "New Zealand" , "New Zealand" , "Pakistan" , "Pakistan" , "West Indies","New Zealand"];

var recipientsArray = countries.sort(); 
checkedWords = [];

for (var i = 0; i < recipientsArray.length; ++i) {
    var count = 0;

  for(var j=i;j<recipientsArray.length;j++){
    if(checkedWords.indexOf(recipientsArray[i]) > -1){
        continue;
    }
    if(recipientsArray[i] == recipientsArray[j]){
        count = count+1;
    }
  }
  console.log(count);
  if(count >= 3){
    alert(recipientsArray[i]);
  }
  checkedWords.push(recipientsArray[i]);
}

https://jsfiddle.net/74bzzze3/

我希望这能回答你的问题：）

Answer 3

＆＃13;

const array = ['India' , 'Australia' , 'Bangladesh' , 'India' , 'India' , 'New Zealand' , 'New Zealand' , 'Pakistan' , 'Pakistan' , 'West Indies'];


_.each(_.uniq(_.filter(array, function(v) {
    return _.filter(array, function(v1) {
        return v1 === v;
    }).length > 2;
})), function(i) {
    console.log(i);
});

＆＃13;

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>

＆＃13;

使用UnderscoreJS：

_.uniq(_.filter(array, v => 
  _.filter(array, v1 => v1 === v).length > 2));

<强>代码

_.each(_.uniq(_.filter(array, function(v) {
    return _.filter(array, function(v1) {
        return v1 === v;
    }).length > 2;
})), function(i) {
    console.log(i);
});

演示 https://jsfiddle.net/sumitridhal/e9yf3txg/3/

使用jquery检查Array中的项目数

3 个答案: