Does JavaScript support block scope?

JavascriptWeb DevelopmentObject Oriented Programming

JavaScript supports block scope only for variables that were declared using let or const keyword. Variables declared using var support function scope but not block scope.

Following is the code for displaying block scope 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;
   }
   .result {
      font-size: 20px;
      font-weight: 500;
      color: blueviolet;
   }
</style>
</head>
<body>
<h1>Block scope JavaScript</h1>
<div class="result"></div>
<br />
<button class="Btn">Click Here</button>
<h3>Click on the above button to create variables with var and let keyword and access them</h3>
<script>
   let resEle = document.querySelector(".result");
   let BtnEle = document.querySelector(".Btn");{
      let a = 22;
   }
   {
      var b = 44;
   }
   BtnEle.addEventListener("click", () => {
      try {
         resEle.innerHTML = a;
      } catch (err) {
         resEle.innerHTML = err + "<br>";
      }
      resEle.innerHTML += "var b = " + b;
   });
</script>
</body>
</html>

Output

On clicking the ‘Click Here’ button −


raja
Published on 18-Jul-2020 08:02:08
Advertisements