Send image from html to node.js

Question

Hi I am capturing frames from video and converting it in Image. But when i pass this image to server.js I am not able to access it and getting its type as undefined on console.This is my script code:

var canvas= document.getElementById("canvs");
var video=document.getElementById("videoElement");
var png= new Image();
var imcanvas = canvas.getContext("2d");
imcanvas.drawImage(video, 0,0 , canvas.width,canvas.height);	
png = canvas.toDataURL("image/png");
var json={"name":png};
jQuery.ajax({
	url: "/demo",
	type: "POST",
	data:json,
	processData: false,
	cache: false,
	success: function(reponse) {
	  if(reponse) {
	    console.log(reponse);
	  } else {
	    console.log('Error');
	  }
	}
});

This is my server.js

var express = require('express');
var cv = require('./public/opencv');
const bodyParser = require('body-parser');
var app = express();
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended:true }));
app.use(express.static('public'));
app.get('/index.html', function (req, res) {
	res.sendFile( __dirname + "/" + "index.html" );
});
app.post('/demo', (req,res)=>{
	console.log(typeof(req.body.name));
});
var server = app.listen(8081, function () {
	var host = server.address().address;
	var port = server.address().port;
});

Shubham srivastava · Accepted Answer · 2018-06-07 15:40:34Z

2

Thanks @FewFlyBy.You answered it, only one extra statement i added in server.js. I am able do it like this :

         //above codes
        jQuery.ajax({
                url: "/demo",
                type: "post",
                dataType: 'json',
                contentType: "application/json; charset=utf-8",
                data: JSON.stringify(json),
                success: function (reponse) {
                    if (reponse) {
                        console.log(reponse);
                    } else {
                        console.log('Error');
                    }
                }
                });

and in server.js

    //require statements
    app.use(bodyParser.json({limit: '50mb'}));
    app.use(bodyParser.urlencoded({
       limit: '50mb',
       extended: true
    }));
    app.post('/demo', (req, res) => {
    const base64data=req.body.image;
    }

answered Jun 7, 2018 at 15:40

Shubham srivastava

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1 Comment

wobsoriano Over a year ago

Congratulations. Keep it up!

wobsoriano · Accepted Answer · 2018-06-04 08:03:33Z

1

It's probably the body's limit.

What you can do is to set the body-parser limit like this:

 app.use(bodyParser.urlencoded({
    limit: '50mb',
    extended: true
 }));

If it's still undefined, try to add dataType prop in your request and stringify the json data. Example:

var json={"name":png};

jQuery.ajax({
    url: "/demo",
    dataType  : 'json',
    type: "POST",
    data: JSON.stringify(json),
    processData: false,
    cache: false,
    success: function(reponse) {
        if(reponse) {
            console.log(reponse);
        } else {
            console.log('Error');
        }
    }
})

edited Jun 4, 2018 at 8:03

answered Jun 4, 2018 at 7:39

wobsoriano

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1 Comment

Shubham srivastava Over a year ago

Thanks for reply but still i am getting undefined. Is there any other way to pass image to node.js?

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