The For In Loop

The JavaScript for in statement loops through the properties of an Object:

Syntax

for (key in object) {

 // code block to be executed

}

Example

 <!DOCTYPE html>

      <html>

      <body>

 <h2>JavaScript For In Loop</h2>

      <p>The for in statement loops through the properties of an object:</p>

  <p id="demo"></p>

  <script>

 // Define an object named 'person' with properties
const person = {fname:"John", lname:"Doe", age:25}; 

  // Initialize an empty string 'txt'
 let txt = "";

  // For...in loop to iterate through the properties of the 'person' object
for (let x in person) {

  // Concatenate the value of each property to the 'txt' string
 txt += person[x] + " ";

}
 // Display the result in the paragraph with id "demo"
 document.getElementById("demo").innerHTML = txt;

  </script>


      </body>

     </html>

You can click on above box to edit the code and run again.

The For In Loop

Syntax

Example

Output