How to upload file( only image) with nodeJs

Objective: uploading only image which we filters such as 'png', 'jpg' or 'jpeg' file with customized file name. Here are source code github

We use expressjs framework with multer middleware for handling file upload

Multer is a node.js middleware for handling multipart/form-data, which is primarily used for uploading files. It is written on top of busboy for maximum efficiency.

NOTE: Multer will not process any form which is not multipart (multipart/form-data). 

Implementation
+ View file: add enctype="multipart/form-data"

<form action="/" method="post" enctype="multipart/form-data">
    <input type="file" name="imageFile">
    <input type="submit">
</form>

+ Create function for filtering file extension.

function fileFilter(req, file, cb){
    var extensions = ['png','jpg','jpeg'];
    var bool = false;
    var extensionFile = getExtension(file);
    for(var i=0; i<extensions.length; i++){
        if(extensionFile == extensions[i]){
            cb(null, true);
            bool = true;
        }
    }
    if(!bool) cb(new Error("We support only 'png', 'jpg', jpeg."));
}

function getExtension(file){
    return file.originalname.substr(file.originalname.lastIndexOf(".")+1, file.originalname.length);
}

Throw Error 

+ Define upload directory to be store uploaded file.

var storage = multer.diskStorage({
    destination: function (req, file, cb) {
        cb(null, __dirname + '/uploads')
    },
    filename: function (req, file, cb) {
        cb(null, file.fieldname + '-' + Date.now() + "." + getExtension(file));
    }
});

var upload = multer({ storage: storage, fileFilter: fileFilter });

+ use middleware to upload url

app.use('/',upload.single('imageFile'), index);

Source Code: download here
Reference: https://www.npmjs.com/package/multer