How to validate upload file size and file extension using JavaScript?

Today, We want to share with you file upload size limit validation in javascript.In this post we will show you file upload validation in javascript, hear for Validation of file size while uploading using JavaScript / jQuery we will give you demo and example for implement.In this post, we will learn about input type file size limit javascript with an example.

How to validate upload file size and file extension using JavaScript ?

index.html

 Note: Please select only image file (eg: .png, .jpeg, .jpg, .gif etc)
 Max File size : 1MB allowed 






$(function() {
$("#file").change(function () {
	    if(fileExtValidate(this)) {
	    	 if(fileSizeValidate(this)) {
	    	 	showImg(this);
	    	 }	 
	    }    
    });

// File extension validation, Add more extension you want to allow
var validExt = ".png, .gif, .jpeg, .jpg";
function fileExtValidate(fdata) {
 var filePath = fdata.value;
 var getFileExt = filePath.substring(filePath.lastIndexOf('.') + 1).toLowerCase();
 var pos = validExt.indexOf(getFileExt);
 if(pos < 0) {
 	alert("This file is not allowed, please upload valid file.");
 	return false;
  } else {
  	return true;
  }
}

// file size validation
// size in kb
var maxSize = '1024';
function fileSizeValidate(fdata) {
	 if (fdata.files && fdata.files[0]) {
                var fsize = fdata.files[0].size/1024;
                if(fsize > maxSize) {
                	 alert('Maximum file size exceed, This file size is: ' + fsize + "KB");
                	 return false;
                } else {
                	return true;
                }
     }
 }

 // display img preview before upload.
function showImg(fdata) {
        if (fdata.files && fdata.files[0]) {
            var reader = new FileReader();

            reader.onload = function (e) {
                $('#img').attr('src', e.target.result);
            }

            reader.readAsDataURL(fdata.files[0]);
        }
    }

	
});

Get File Size using JavaScript

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Get File Size using jQuery

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I hope you get an idea about File upload size validation using jQuery with demo.
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