I have two lists like these: and combined them using zip: Then, I want to apply a map on the zip like this, for example: The ‘item’ in the code above implicitly has an ‘any’ type, so I want to define the type like: but this doesn’t work. Does anyone know how to define the type, f…
Tag: syntax
What is an “Object” in a JavaScript NodeJS code?
I saw the following code: And I can not understand what is the Object in this line of code: I mean is it instance of a class? What class? Where did it instantiated? What does this Object refer to? Answer An object in Node.JS is anything that’s within curly brackets, JSON basically. And if you actually r…
Calculation based on variable containing multiple possible substrings
I have 2 variables (source and platform) that has results such as: “Source”: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36 Edg/100.0.1185.44 etc. “Platform”: Win32 etc. I want to create 2 new variables (device and system), “extracted…
When to use : and = in javascript?
I have these code snippet. and How do I know when to use ‘=’ and when to use ‘:’ in javascript? Answer = inside a function or code block (like inside an if/else/for/while etc.), : inside of objects.
The difference in syntax for updating an object item
What is the difference between: and Answer The first is an assignment to cartItem, while the second is a mutation of the object held by cartItem. The first creates a new object. The previous value of cartItem referenced an object that could still be referenced by another reference. Demo: So there is a differe…
When I enter the terminal command “$ node fileName.js” the concole throws out a “SyntaxError: Unexpected token ‘<'" error
My Env.: React v17.0.2 node v16.6.1 npm v7.20.3 VS Code Windows 10 The Problem: I am currently working on a cooking recipe app for a friend’s website. My issue is that whenever I enter “node fileName.js” into my terminal to run and check the console.log’s and other outputs for my code,…
Calling a Self-Executing Function from an Event Listener
Assume this is my only HTML And assume this is my only JavaScript I want to execute a function whenever the input changes, but I also want to execute said function once when the page is loaded (Self-Executing Function or IIFE). Below are 3 examples, 1 of which doesn’t work. The following works as expect…
Can I use ES6’s arrow function syntax with generators? (arrow notation)
That is, how do I express with arrow syntax? I’ve tried all the combinations I could think of, and I can’t find any documentation on it. (I am currently using Node.js v0.11.14.) Answer Can I use ES6’s arrow function syntax with generators? You can’t. Sorry. According to MDN The functio…
Use of commas versus semicolons?
Given the following code: As can be seen, there is a mix of both. What would be the benefit of using one or the other? My understanding is that the semicolon is to end the statement. And comma should be used to string together multiple declarations. So is it safe to say that with this example then there shoul…
Parse indentation level with PEG.js
I have essentially the same question as PEG for Python style indentation, but I’d like to get a little more direction regarding this answer. The answer successfully generates an array of strings that are each line of input with ‘INDENT’ and ‘DEDENT’ between lines. It seems like h…