Assuming w has not been previously defined, the following JS code gives ReferenceError: w is not defined: whereas this code simply returns undefined: Why does the ?. operator not treat not defined as undefined? Answer This is mentioned in the documentation Optional chaining cannot be used on a non-declared ro…
Tag: javascript
Module blocked because of a disallowed MIME type (“text/html”)
I am getting module block error when ever I try to import firebase module My code is as followed : My file architecture is : Answer By using this line: You are requesting the browser to fetch the Firebase App library module from the URL https://yourproject.web.app/firebase/app. Because the .js extension is mi…
How to select all objects within an array by their key and add their values together?
So here’s what I’m trying to do, I have an application I’ve been working on that allows users to read articles and take quizzes on them, each article is contained in a category. Category has an _id which is unique. Quiz attempts are held within another table which refrences the article, whic…
How to change the values of colSpan with toggle buttons
I have total of 7 buttons which toggle hide and show of columns. For example, if button 1 is pressed once it will hide column 1 and if button 1 is again pressed it will show column 1 and the rest 6 buttons perform the same operation. But is it possible that if I click any one button from the
add border when mouse hovered on MUI v5 table row
I created a table with Material UI v5 and now when the mouse pointer hovered on the table row I want to add a blue border to the table row. I have tried a lot of ways and searched but I did not find any solution. this is what I made so far: codesandbox Answer You can check the online
Why is the function cell.getTable undefined in Tabulator’s titleFormatter function?
Our client is insisting on a custom-styled checkbox. Ok, no problem, I’ll put in a custom formatter function and return the svg/html required. However I have come stuck at header column checkbox. I have been unable to access the table data to determine what state to show (and toggle all rows). The cell …
Remove page numbers on pages once user completes there printing html + Javascript
this solution worked for me to add page numbers to my HTML once the user clicks ctrl + P. how can I have the script remove the page numbers once the users finished the print job? (not sure how to remove a function with javascript) I used this solution to implement the JavaScript code: https://stackoverflow.co…
Error in Firebasse”assert.ts:128 Uncaught FirebaseError: Firebase: Error (auth/invalid-api-key)
Why do I have the error that it says invalid API keys? This is the sample .env.local In another file: This is the error: The Package.json: Answer Make sure your .env.local is placed in the root directory, and not in any subfolders like src or public. Other than that, nothing seems to be wrong with your code. …
Leaflet geoman “Button with this name already exists” error when creating a new button in react
I am trying to create a custom button for arrows in the drawing tool of leaflet-geoman. The idea was to work with the copyDrawControl function, and to use Line as a model to make Polylines with arrow tips. I wrote a code mostly inspired from this demonstration https://codesandbox.io/s/394eq?file=/src/index.js…
Calculate width of hexagons in a field
I am drawing a hexagonal grid using javascript and svg. The grid needs to have a fixed width (let’s say, of 1000px). The dimensions of the grid can differ, but I have that information (the columns and rows). I have written a function that given a hexagons ‘bounding box’ width (the height is …