Explain "for...in" statement in JavaScript?

Javascript Web Development Object Oriented Programming

The for…in loop loops through all of the object properties. Following is the code o implement the for..in statement in JavaScript −

Example

Live Demo

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .sample,.result {
      font-size: 18px;
      font-weight: 500;
      color: red;
   }
</style>
</head>
<body>
<h1>"for...in" statement in JavaScript</h1>
<div class="sample">
{"firstName":"Rohan","lastName":"Sharma","age":22}
</div>
<div class="result" style="color: green;"></div>
<button class="Btn">CLICK HERE</button>
<h3>Click on the above button to traverse the above object using for..in loop</h3>
<script>
   let sampleEle = document.querySelector(".sample");
   let resultEle = document.querySelector(".result");
   let obj = JSON.parse(sampleEle.innerHTML);
   document.querySelector(".Btn").addEventListener("click", () => {
      for (let i in obj) {
         resultEle.innerHTML += "Property = " + i + " : Value = " + obj[i] + "<br>";
      }
   });
</script>
</body>
</html>