Magento file validation - prototype
Add file extension validation in magento form by using below code. Validation.add('validate-jpg-png','Please upload only jpg/png file format!',function(the_field_value){ //console.log(the_field_value); if(the_field_value == '') return true; var extension = the_field_value.replace(/^.*\./, ''); if (extension == the_field_value) { extension = ''; } else { extension = extension.toLowerCase(); } switch (extension) { case 'jpg': return true; case 'png': return true; //you can add more case for valid extension. default: return false; } }); To make it work add validate-jpg-png class to input file type.