JavaScript counts the number of times a character appears

This article example shares the specific code of JavaScript to count the number of times a character appears for your reference. The specific content is as follows

Counts the number of times each character occurs in the user input string.

For example: the input string is "abca12abbc121d", the output is: a appears 3 times, b appears 3 times, c appears 2 times, d appears 1 time, 1 appears 3 times, and 2 appears 2 times.

Method 1

<script>
 var ary = "abca12abbc121d";
 
 var obj = {};
 var i = 0;
 ary1 = ary.toLocaleLowerCase(); 
 
 for(i = 0; i < ary1.length; i++)
 {
 key = ary1[i];
 if(obj[key])
 {
 //The object contains this letter obj[key]++;
 }
 else
 {
 //The object does not have this letter, add the letter to the object obj[key] = 1;
 }
 }
 
 for(var key in obj) //Traverse this object {
 console.log(key + "This character appears" + obj[key] + "times");
 }
</script>

The effect is as follows:

This method is implemented using developer tools

Method 2

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
 <script src="sc/char-sunmmary.js"></script>
 <script>
 window.onload = function(){
  var txtChars = document.getElementById("txt-chars");
  var show = document.getElementById("show");
  document.getElementById("btn-ok").onclick=function(){
  var str=txtChars.value;
  var charTotal = total(str);
  // Descending charTotal.sort(function(a,b){
   return (a.count-b.count)*-1;
  })
  
  show.innerHTML="<ul>";
  //slice(0,5) takes the first five for(var ct of charTotal.slice(0,5)){
   show.innerHTML+="<li>"+ct.char+" appeared "+ct.count+" times</li>";
  }
  show.innerHTML+="</ul>";
  }
 }
 </script>
</head>
<body>
 <label for="txt-chars">Please enter a string of characters:</label>
 <input type="text" id="txt-chars" name=""/>
 <button id="btn-ok">OK</button>
 <p id="show"></p>
</body>
</html>

char-sunmmary.js

function Summary(char,count) {
 this.char=char;
 this.count=count;
}
// Pass a string and return the frequency of occurrence function total(str) {
 var result = [];
 for(var c of str){
 var charObj = checkChar(result,c);
 if(charObj==null){
  result.push(new Summary(c,1));
 }
 else{
  charObj.count++;
 }
 }
 return result;
}
// Search for the summary instance containing the character char in the array arr // If it exists, return the instance, otherwise return null
function checkChar(arr,char) {
 var r=null;
 for(var c of arr){
 if(c.char==char){
  r=c;
  break;
 }
 }
 return r;
}

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.

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