How do I use backend variable in ejs script section?

Question

 <!-- begin snippet: js hide: false console: true babel: false -->

 <script> // initialize the map var map = L.map('map').setView([25.037393872113785, 121.56372070312499], 12); // load a tile layer var baseLayer = L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', { attribution: '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>', maxZoom: 17 }).addTo(map); var Data = var cfg = { "radius": 0.03, "maxOpacity": 0.5, "scaleRadius": true, "useLocalExtrema": true, latField: 'lat', lngField: 'lng', valueField: 'count' }; var heatmapLayer = new HeatmapOverlay(cfg).addTo(map); heatmapLayer.setData(Data); </script>

//javascript version = 1.7
var express = require('express');
var router = express.Router();
var r = require('rethinkdb');
var rethinkdbHost = IP;
var connection = null;
var waterfall = require('async-waterfall');

r.connect( {host: rethinkdbHost, port: 28015}, function(err, conn) {
    if (err) throw err;
    connection = conn;
    r.db('AQI_inference').table('pm25_one_week')).run(connection, function(err, cursor) {
        if (err) throw err;
        cursor.toArray(function(err, result) {
            if (err) throw err;
                var cor = result.geometry.coordinates;
                var t = result.properties.time;
                var pm25 = result.properties.col;
                console.log(cor, t, pm25);
                router.get('/', function(req, res, next) {
                    res.render('mapTest', {cor: cor,time: t, pm25: pm25});
                 });
            });
        });
    });

I just learned nodejs express for a week

I want to make a map with air quality mark on it and got some problem now,

I get data from rethinkDB and I can only access the data with <% =%>

How do I use the variable cor, time and pm25 in frontend script section?

I want to use cor in 'var Data' in my js code.

is there any simple way to do this?

please help me

Answer 1

use some element for storing data elements.

<div id="script" data-time="<%= time %>" data-cor="<%= cor %>"></div>

In you script tag you can access using

var time = document.getElementById("script").getAttribute('data-time');

similarly you can use other variables.