将值从 node.js 传递给 javascript

Question

I'm trying to work with Google's example code: PhotoFrame . It is built with node.js, expressjs, jQuery, etc. I need to pass a variable -- let's call it myString -- from app.js to one of the .js files -- let's call it myScript.js. I've tried at least a dozen approaches that I found at StackOverflow and elsewhere. None has worked.

Some folks have said "just use a global, even though they're 'BAD'. In app.js you:

global.myStringGlobal = myString

and in myScript you:

var myStringLocal = myStringGlobal;

Doesn't work: myStringGlobal is undefined.

Some folks say: code a little object in app.js and module.export it. Them require it in myScript. Doesn't work: require is undefined in myScript. In fact, since myScript and myOtherScripts run in the browser, require is simply un-available.

Some folks say code this in app.js:

res.render(page, {myString: myString});

Others say "No, that sends myString to the html renderer; not to myString. They're correct.

I won't drag this out by telling you the other ways I tried in vain.

This question has been asked and answered many times in various ways, but none of the answers work -- anymore? or who knows why?

So I ask again: does anyone know how to pass a variable from the node.js app.js script to some myScript.js file?

Answer 1

Here's the explanation.

You have to know that you have been involved into different app. Your express app is a server side app, while another would be client side app. So, the main question is, how to pass data from server to client?

If you're thinking about ajax , then you're right. I'm not using jQuery anymore, but I think you can use something like $.get(..) .

server

const express = require('express');
const app = express();
const port = 8080;

// Data can be requested via GET method
app.get('/sample-api', (req, res) => {
    res.json({ text: 'Lorem Ipsum' });
});

// You can render page here...

app.listen(port, () => console.log(`Listening on port ${port}`);

client

$(function() {
    var msgFromServer;
    $.get( "/sample-api", function( data ) {
        msgFromServer = data.text;
        alert( "Received data from server!" );
    });
});

Answer 2

From Expressjs, you can pass a variable along with a page when you render it . In the render call, you name the view you're trying to render and you can pass variables along with it:

app.render('email', { name: 'Tobi' }, function(err, html){
  // ...
});

This passes a variable named 'name' to the email view with the value 'Tobi'. You can then use the variable in the HTML

<script>var name = "<%= name %>";</script>

See previous question