Cannot read property ‘getContext’ of null, using canvas
I guess the problem is your js runs before the html is loaded. If you are using jquery, you can use the document ready function to wrap your code: Or simply put your js after the <canvas>.
javascript
Basic Ajax send/receive with node.js
Your request should be to the server, NOT the server.js file which instantiates it. So, the request should look something like this: xmlhttp.open(“GET”,”http://localhost:8001/”, true); Also, you are trying to serve the front-end (index.html) AND serve AJAX requests at the same URI. To accomplish this, you are going to have to introduce logic to your server.js that will … Read more
XMLHttpRequest status 0 (responseText is empty)
status is 0 when your html file containing the script is opened in the browser via the file scheme. Make sure to place the files in your server (apache or tomcat whatever) and then open it via http protocol in the browser. (i.e. http://localhost/myfile.html) This is the solution.
Is JavaScript supported in an email message?
http://en.wikipedia.org/wiki/Comparison_of_e-mail_clients Old clients, such as Lotus Notes, Mozilla Thunderbird, Outlook Express, and Windows Live Mail all seem to have supported some sort of JavaScript execution. Nothing else does. It seems like a bad idea security-wise, so I would expect this to be a feature that won’t always be around, even in these clients.
What does “export default” do in JSX?
Export like export default HelloWorld; and import, such as import React from ‘react’ are part of the ES6 modules system. A module is a self contained unit that can expose assets to other modules using export, and acquire assets from other modules using import. In your code: In ES6 there are two kinds of exports: Named exports – for example export function func() {} is a named … Read more
How to move all HTML element children to another parent using JavaScript?
Basically, you want to loop through each direct descendent of the old-parent node, and move it to the new parent. Any children of a direct descendent will get moved with it. External link
How to set the id attribute of a HTML element dynamically with angularjs (1.x)?
ngAttr directive can totally be of help here, as introduced in the official documentation For instance, to set the id attribute value of a div element, so that it contains an index, a view fragment might contain which would get interpolated to
How to subtract date/time in JavaScript?
This will give you the difference between two dates, in milliseconds In your example, it’d be You need to make sure that compareDate is a valid Date object. Something like this will probably work for you i.e. turning “2011-02-07 15:13:06” into new Date(‘2011/02/07 15:13:06’), which is a format the Date constructor can comprehend.
How can I check if an element exists in the visible DOM?
It seems some people are landing here, and simply want to know if an element exists (a little bit different to the original question). That’s as simple as using any of the browser’s selecting method, and checking it for a truthy value (generally). For example, if my element had an id of “find-me”, I could … Read more
Pass a JavaScript function as parameter
You just need to remove the parenthesis: This then passes the function without executing it first. Here is an example: