What does the function then() mean in JavaScript?
I’ve been seeing code that looks like: Where does then() come from?
javascript
What does [object Object] mean?
The default conversion from an object to string is “[object Object]”. As you are dealing with jQuery objects, you might want to do to print the element’s ID. As mentioned in the comments, you should use the tools included in browsers like Firefox or Chrome to introspect objects by doing console.log(whichIsVisible()) instead of alert. Sidenote: … Read more
React.js: Set innerHTML vs dangerouslySetInnerHTML
Yes there is a difference! The immediate effect of using innerHTML versus dangerouslySetInnerHTML is identical — the DOM node will update with the injected HTML. However, behind the scenes when you use dangerouslySetInnerHTML it lets React know that the HTML inside of that component is not something it cares about. Because React uses a virtual … Read more
Uncaught ReferenceError: jQuery is not defined [duplicate]
This question already has answers here: Uncaught ReferenceError: $ is not defined? (40 answers) Closed 5 years ago. I have implemented some JavaScript on my site but I keep getting the following error messages: Uncaught ReferenceError: jQuery is not defined and Uncaught SyntaxError: Unexpected token < This is the JavaScript that I am using in … Read more
How to fix “Cannot read property ‘addEventListener’ of null” error [duplicate]
You are loading the Javascript file in the <head>, before the body of your HTML Is loaded. Therefore your line Has nothing to look up – your button with class guessSubmit doesn’t exist yet. And since guessSubmit is null, it does not contain any properties, hence the error. The easiest solution is to put your … Read more
ReferenceError: $ is not defined
Add jQuery library before your script which uses $ or jQuery so that $ can be identified in scripts.
TypeError: Converting circular structure to JSON in nodejs
JSON doesn’t accept circular objects – objects which reference themselves. JSON.stringify() will throw an error if it comes across one of these. The request (req) object is circular by nature – Node does that. In this case, because you just need to log it to the console, you can use the console’s native stringifying and … Read more
What is JSONP, and why was it created?
It’s actually not too complicated… Say you’re on domain example.com, and you want to make a request to domain example.net. To do so, you need to cross domain boundaries, a no-no in most of browserland. The one item that bypasses this limitation is <script> tags. When you use a script tag, the domain limitation is … Read more
SyntaxError: Unexpected token o in JSON at position 1
The JSON you posted looks fine, however in your code, it is most likely not a JSON string anymore, but already a JavaScript object. This means, no more parsing is necessary. You can test this yourself, e.g. in Chrome’s console: JSON.parse() converts the input into a string. The toString() method of JavaScript objects by default … Read more
Error OPTIONS net::ERR_CONNECTION_REFUSED
I am developing a web application using “jQuery”(front-end) and “Python”(back-end). While making a PUT request to update details in the database, this is the error I get in the console: OPTIONS “REST API URL” net::ERR_CONNECTION_REFUSED My jQuery code is: I read about how HTTP Requests other than GET and POST are first pre-flighted as OPTIONS … Read more