I'm setting up a HTML page that want to use the data from CertStream.
The Javascript library is located at https://github.com/CaliDog/certstream-js
In the install instructions it says " if you're using this in the browser, just add dist/certstream.min.js to a tag, and interact with it as normal!".
I have therefor created a HTML page that uses this tag:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Certstream</title>
<meta name="viewport" content="width=device-width; initial-scale=1.0;"/>
<meta http-equiv="Content-Type" content="text/html; charset=UFT-8" />
</head>
<body>
<h1>CertStream</h1>
<!-- CertStream script -->
<script src="dist/certstream.min.js"></script>
<script>
const CertStreamClient = require('certstream');
let client = new CertStreamClient(function(message){
console.log("Received -> ", message)
});
client.connect();
</script>
<!-- //CertStream script -->
</body>
</html>
But I get the error:
Uncaught ReferenceError: require is not defined
http://localhost/certstream-js/test.html:15
certstream.min.js is located on in the folder "dist":
!function(e,t){"object"==typeof exports&&"object"==typeof module?module.exports=t():"function"==typeof define&&define.amd?define([],t):"object"==typeof exports?exports.CertStream=t():e.CertStream=t()}(this,function(){return function(e){function t(o){if(n[o])return n[o].exports;var c=n[o]={exports:{},id:o,loaded:!1};return e[o].call(c.exports,c,c.exports,t),c.loaded=!0,c.exports}var n={};return t.m=e,t.c=n,t.p="",t(0)}([function(e,t,n){"use strict";function o(e){return e&&e.__esModule?e:{default:e}}function c(e,t){if(!(e instanceof t))throw new TypeError("Cannot call a class as a function")}Object.defineProperty(t,"__esModule",{value:!0});var r=function(){function e(e,t){for(var n=0;n<t.length;n++){var o=t[n];o.enumerable=o.enumerable||!1,o.configurable=!0,"value"in o&&(o.writable=!0),Object.defineProperty(e,o.key,o)}}return function(t,n,o){return n&&e(t.prototype,n),o&&e(t,o),t}}(),i=n(1),s=o(i),a=function(){function e(t){var n=arguments.length>1&&void 0!==arguments[1]&&arguments[1];c(this,e),this.context={},this.callback=t,this.skipHeartbeats=n}return r(e,[{key:"connect",value:function(){var e=this;console.log("Connecting..."),this.ws=new s.default("wss://certstream.calidog.io/"),console.log("Created ws -> ",this.ws),this.ws.onmessage=function(t){console.log("onmessage called!");var n=JSON.parse(t.data);"heartbeat"===n.message_type&&e.skipHeartbeats||e.callback(t,e.context)},this.ws.onopen=function(){console.log("Connection established to certstream! Waiting for messages...")},this.ws.open()}}]),e}();t.default=a},function(e,t,n){var o,c,r;!function(n,i){c=[],o=i,r="function"==typeof o?o.apply(t,c):o,!(void 0!==r&&(e.exports=r))}(this,function(){function e(t,n,o){function c(e,t){var n=document.createEvent("CustomEvent");return n.initCustomEvent(e,!1,!1,t),n}var r={debug:!1,automaticOpen:!0,reconnectInterval:1e3,maxReconnectInterval:3e4,reconnectDecay:1.5,timeoutInterval:2e3,maxReconnectAttempts:null};o||(o={});for(var i in r)"undefined"!=typeof o[i]?this[i]=o[i]:this[i]=r[i];this.url=t,this.reconnectAttempts=0,this.readyState=WebSocket.CONNECTING,this.protocol=null;var s,a=this,u=!1,l=!1,d=document.createElement("div");d.addEventListener("open",function(e){a.onopen(e)}),d.addEventListener("close",function(e){a.onclose(e)}),d.addEventListener("connecting",function(e){a.onconnecting(e)}),d.addEventListener("message",function(e){a.onmessage(e)}),d.addEventListener("error",function(e){a.onerror(e)}),this.addEventListener=d.addEventListener.bind(d),this.removeEventListener=d.removeEventListener.bind(d),this.dispatchEvent=d.dispatchEvent.bind(d),this.open=function(t){if(s=new WebSocket(a.url,n||[]),t){if(this.maxReconnectAttempts&&this.reconnectAttempts>this.maxReconnectAttempts)return}else d.dispatchEvent(c("connecting")),this.reconnectAttempts=0;(a.debug||e.debugAll)&&console.debug("ReconnectingWebSocket","attempt-connect",a.url);var o=s,r=setTimeout(function(){(a.debug||e.debugAll)&&console.debug("ReconnectingWebSocket","connection-timeout",a.url),l=!0,o.close(),l=!1},a.timeoutInterval);s.onopen=function(n){clearTimeout(r),(a.debug||e.debugAll)&&console.debug("ReconnectingWebSocket","onopen",a.url),a.protocol=s.protocol,a.readyState=WebSocket.OPEN,a.reconnectAttempts=0;var o=c("open");o.isReconnect=t,t=!1,d.dispatchEvent(o)},s.onclose=function(n){if(clearTimeout(r),s=null,u)a.readyState=WebSocket.CLOSED,d.dispatchEvent(c("close"));else{a.readyState=WebSocket.CONNECTING;var o=c("connecting");o.code=n.code,o.reason=n.reason,o.wasClean=n.wasClean,d.dispatchEvent(o),t||l||((a.debug||e.debugAll)&&console.debug("ReconnectingWebSocket","onclose",a.url),d.dispatchEvent(c("close")));var r=a.reconnectInterval*Math.pow(a.reconnectDecay,a.reconnectAttempts);setTimeout(function(){a.reconnectAttempts++,a.open(!0)},r>a.maxReconnectInterval?a.maxReconnectInterval:r)}},s.onmessage=function(t){(a.debug||e.debugAll)&&console.debug("ReconnectingWebSocket","onmessage",a.url,t.data);var n=c("message");n.data=t.data,d.dispatchEvent(n)},s.onerror=function(t){(a.debug||e.debugAll)&&console.debug("ReconnectingWebSocket","onerror",a.url,t),d.dispatchEvent(c("error"))}},1==this.automaticOpen&&this.open(!1),this.send=function(t){if(s)return(a.debug||e.debugAll)&&console.debug("ReconnectingWebSocket","send",a.url,t),s.send(t);throw"INVALID_STATE_ERR : Pausing to reconnect websocket"},this.close=function(e,t){"undefined"==typeof e&&(e=1e3),u=!0,s&&s.close(e,t)},this.refresh=function(){s&&s.close()}}if("WebSocket"in window)return e.prototype.onopen=function(e){},e.prototype.onclose=function(e){},e.prototype.onconnecting=function(e){},e.prototype.onmessage=function(e){},e.prototype.onerror=function(e){},e.debugAll=!1,e.CONNECTING=WebSocket.CONNECTING,e.OPEN=WebSocket.OPEN,e.CLOSING=WebSocket.CLOSING,e.CLOSED=WebSocket.CLOSED,e})}])});
//# sourceMappingURL=certstream.min.js.map
What they mean by
...if you're using this in the browser, just add dist/certstream.min.js to a tag, and interact with it as normal!
...is that you don't need the require call (require is CommonJS, not standard JavaScript, and not provided by default on browsers). If you just include the script file in your page, it defines a global CertStream object with a default property providing the default export of the module. (I suspected this was the case, so I grabbed a copy and tried it.)
The docs could be clearer.🙂 In particular, it looks like after including the library in the browser, you have to use CertStream.default rather than CertStreamClient. I'd probably do that by doing this up-front:
const CertStreamClient = CertStream.default;
(It's too bad they don't provide a native JavaScript module [ESM] file in their dist folder.)
I looked up into certstream.js module in the dist folder and it is a UMD module. Basically, a UMD module is a JavaScript file that tries to guess at runtime which module system it’s being used in, and then it acts as that kind of module. So you can load the file in a plain <script>, or you can load it from an AMD module loader, or you can load it as a Node.js module, and it will always do something sensible.
In your code since you have already loaded the module using <script> tag, the global CertStream object can be directly used without requiring the module again.
My javascript app is for a kiosk and is only targeting the Chrome browser. I'm using Chrome version 65. I am trying to use ES6 modules without using a transpiler like Babel. My code was originally:
in index.html:
<script src="js/index.js"></script>
index.js:
import Main from './classes/Main.js';
const init = () => {
const app = new Main();
};
init();
Main.js:
export default class Main {
constructor() {
}
}
Originally I got the error "Uncaught SyntaxError: Unexpected identifier" from index.js line 1. Then based on ES6 module Import giving "Uncaught SyntaxError: Unexpected identifier" I added 'type="module"' to the html tag:
<script type="module" src="js/index.js"></script>
This did load, but it takes my browser about 15 seconds to load index.js and main.js according to the network profiler. What could be going on?
So I ran some tests on my local box. I have a simple NodeJs server running with the following three files:
index.html
<!doctype html>
<html>
<head>
<title>es6 Module test</title>
<script>
console.time('load module');
console.time('time until constructor called');
</script>
<script type="module" src="module.js"></script>
<script>
console.timeEnd('load module');
</script>
</head>
<body>
See console output.
</body>
</html>
module.js
import Main from './Main.js';
const init = () => {
const app = new Main();
};
init();
and
Main.js
export default class Main {
constructor() {
console.timeEnd('time until constructor called');
}
}
Running this code in Chrome 65 (On a Mac)
I get the following output:
Run 1
load module: 0.141845703125ms
time until constructor called: 7.90087890625ms
Run 2
load module: 0.139892578125ms
time until constructor called: 6.5498046875ms
Run 3
load module: 0.160888671875ms
time until constructor called: 7.14404296875ms
Run 4
load module: 0.297119140625ms
time until constructor called: 7.4228515625ms
My download times ranged between 2ms and 10ms for each of the three files.
I really can't tell why your times are so much slower. But they should not be. Maybe your server is getting hammered and unable to respond fast enough?
Possible things to check:
What happens if you try to download each of the files from the address bar? Do they still take forever to download?
What about on a different server?
I was was having the same problem when serving my files using:
python -m SimpleHTTPServer
After changing to use python3 http.server instead it fixed the problem:
python3 -m http.server
I am trying to instantiate PouchDB in a javascript file. I am importing it with below code :
var imported = document.createElement('script');
imported.type = 'text/javascript';
imported.src = 'pouchdb-6.1.2.js';
document.head.appendChild(imported);
Inside my custom function I am instantiating it as :
var db = new PouchDB('mydb');
This, however, is throwing an error - 'Uncaught ReferenceError: PouchDB is not defined'. Please Help
Did you try this to see if it works:
imported.src='//cdn.jsdelivr.net/pouchdb/6.2.0/pouchdb.min.js'
Also, you can try to add the script tag inside HTML:
<head>
<script src="//cdn.jsdelivr.net/pouchdb/6.2.0/pouchdb.min.js"></script>
</head>
Download the latest PouchDb minified here: https://github.com/pouchdb/pouchdb/releases/download/6.2.0/pouchdb-6.2.0.min.js
Put it in your js or scripts folder and the list it in your index.html file:
<script type="text/javascript" src="js/pouchdb-6.2.0.min.js"></script>