Validation in JavaScript Uploader control

08 May 2023 / 4 minutes to read

The uploader component validate the selected files size and extension using the allowedExtentions, minFileSize and maxFileSize properties. The files can be validated before uploading to the server and can be ignored on uploading. Also, you can validate the files by setting the HTML attributes to the original input element. The validation process occurs on drag-and-drop the files also.

File type

You can allow the specific files alone to upload using the allowedExtentions property. The extension can be represented as collection by comma separators. The uploader component filters the selected or dropped files to match against the specified file types and processes the upload operation. The validation happens when you specify value to inline attribute to accept the original input element.

Source

Preview

app.ts

index.html

import { Uploader } from '@syncfusion/ej2-inputs';

// initialize Uploader component
    let uploadObj: Uploader = new Uploader({
        asyncSettings: {
            saveUrl: 'https://ej2.syncfusion.com/services/api/uploadbox/Save',
            removeUrl: 'https://ej2.syncfusion.com/services/api/uploadbox/Remove'
        },
        allowedExtensions: '.jpg,.png'
    });
    uploadObj.appendTo('#fileupload');

<!DOCTYPE html>
<html lang="en">

<head>
            
    <title>Essential JS 2 Uploader</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 Uploader Component" />
    <meta name="author" content="Syncfusion" />
    <link href="index.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-popups/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-buttons/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
</head>
<body>
    <div id='loader'>Loading....</div>
        <div id='container'>
            <input type="file" id="fileupload" name="UploadFiles"/>
        </div>
    </div>
</body>
</html>

File size

The uploader component allows you to validate the files based on its size. The validation helps to restrict uploading large files or empty files to the server. The size can be represented in bytes. By default, the uploader component allows you to upload minimum file size as 0 byte and maximum file size as 28.4 MB using using the minFileSize and maxFileSize properties.

Source

Preview

app.ts

index.html

import { Uploader  } from '@syncfusion/ej2-inputs';

    // Initialize the uploader component
    let uploadObj: Uploader = new Uploader({
        asyncSettings: {
            saveUrl: 'https://ej2.syncfusion.com/services/api/uploadbox/Save',
            removeUrl: 'https://ej2.syncfusion.com/services/api/uploadbox/Remove'
        },
        minFileSize: 10000,
        maxFileSize: 1500000
    });
    uploadObj.appendTo('#fileupload');

<!DOCTYPE html>
<html lang="en">

<head>
            
    <title>Essential JS 2 Uploader</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 Uploader Component" />
    <meta name="author" content="Syncfusion" />
    <link href="index.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-popups/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-buttons/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
</head>
<body>
    <div id='loader'>Loading....</div>
        <div id='container'>
            <input type="file" id="fileupload" name="UploadFiles"/>
        </div>
    </div>
</body>
</html>

Maximum files count

You can restrict uploading the maximum number of files using the selected event. In the selected event arguments, you can get the currently selected files details using the getFilesData(). You can modify the files details and assign the modified file list to the eventArgs.modifiedFilesData.

Source

Preview

app.ts

index.html

import { enableRipple } from '@syncfusion/ej2-base';
import { Uploader, FileInfo, SelectedEventArgs } from '@syncfusion/ej2-inputs';
import { detach } from '@syncfusion/ej2-base';
import { createSpinner, showSpinner, hideSpinner } from '@syncfusion/ej2-popups';

enableRipple(true);
 let dropElement: HTMLElement = document.getElementsByClassName('control-fluid')[0] as HTMLElement;

    // Initialize the control with file validation
    let uploadObj: Uploader = new Uploader({
        autoUpload: false,
        minFileSize: 10000,
        allowedExtensions: '.doc, .docx, .xls, .xlsx',
        asyncSettings: {
            saveUrl: 'https://ej2.syncfusion.com/services/api/uploadbox/Save',
            removeUrl: 'https://ej2.syncfusion.com/services/api/uploadbox/Remove'
        },
        selected: onFileSelected,
        success: onUploadSuccess,
        dropArea: dropElement
    });
    uploadObj.appendTo('#validation');

    function onFileSelected(args : SelectedEventArgs) : void {
        // Filter the 5 files only to showcase
        args.filesData.splice(5);
        let filesData : FileInfo[] = uploadObj.getFilesData();
        let allFiles : FileInfo[] = filesData.concat(args.filesData);
        if (allFiles.length > 5) {
            for (let i : number = 0; i < allFiles.length; i++) {
                if (allFiles.length > 5) {
                    allFiles.shift();
                }
            }
            args.filesData = allFiles;
            // set the modified custom data
            args.modifiedFilesData = args.filesData;
        }
        args.isModified = true;
    }

    function onUploadSuccess(args: any): void {
        let li: HTMLElement = this.uploadWrapper.querySelector('[data-file-name="' + args.file.name + '"]');
        if (args.operation === 'upload') {
            (li.querySelector('.e-file-delete-btn') as HTMLElement).onclick = () => {
                generateSpinner(this.uploadWrapper);
            };
            (li.querySelector('.e-file-delete-btn') as HTMLElement).onkeydown = (e: any) => {
                if (e.keyCode === 13) {
                    generateSpinner(e.target.closest('.e-upload'));
                }
            };
        } else {
            hideSpinner(this.uploadWrapper);
            detach(this.uploadWrapper.querySelector('.e-spinner-pane'));
        }
    }

    function generateSpinner(targetElement: HTMLElement): void {
        createSpinner({ target: targetElement, width: '25px' });
        showSpinner(targetElement);
    }

<!DOCTYPE html>
<html lang="en">

<head>
            
    <title>Essential JS 2 Uploader</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 Uploader Component" />
    <meta name="author" content="Syncfusion" />
    <link href="index.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-popups/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-buttons/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
</head>
<body>
    <div id='loader'>Loading....</div>
        <div id='container'>
            <input type="file" id="validation" name="UploadFiles"/>
        </div>
    </div>
</body>
</html>

Duplicate files

You can validate the duplicate files before uploading to server using the selected event. Compare the selected files with the existing files data and filter the file list by removing the duplicate files.

Source

Preview

app.ts

index.html

import { enableRipple } from '@syncfusion/ej2-base';
enableRipple(true);
import { Uploader, FileInfo } from '@syncfusion/ej2-inputs';
import { detach, isNullOrUndefined } from '@syncfusion/ej2-base';

    // Initialize the control with file validation
     let uploadObj: Uploader = new Uploader({
        autoUpload: false,
        asyncSettings: {
            saveUrl: 'https://ej2.syncfusion.com/services/api/uploadbox/Save',
            removeUrl: 'https://ej2.syncfusion.com/services/api/uploadbox/Remove'
        },
        selected: onFileSelect,
    });
    uploadObj.appendTo('#validation');

  function onFileSelect(args : any) {
    let existingFiles: FileInfo[] = this.getFilesData();
    for (let i: number = 0; i < args.filesData.length; i++) {
        for(let j: number = 0; j < existingFiles.length; j++) {
            if (!isNullOrUndefined(args.filesData[i])) {
                if (existingFiles[j].name == args.filesData[i].name) {
                    args.filesData.splice(i, 1);
                }
            }
        }
    }
    existingFiles = existingFiles.concat(args.filesData);
    args.modifiedFilesData = existingFiles;
    args.isModified = true;
}

<!DOCTYPE html>
<html lang="en">

<head>
            
    <title>Essential JS 2 Uploader</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 Uploader Component" />
    <meta name="author" content="Syncfusion" />
    <link href="index.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-popups/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/21.2.3/ej2-buttons/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
</head>
<body>
    <div id='loader'>Loading....</div>
        <div id='container'>
            <input type="file" id="validation" name="UploadFiles"/>
        </div>
    </div>
</body>
</html>

You can also explore JavaScript File Upload feature tour page for its groundbreaking features. You can also explore our JavaScript File Upload example to understand how to browse the files which you want to upload to the server.

Validation in JavaScript Uploader control

File type

File size

Maximum files count

Duplicate files

See Also