I am confused about the as const cast. I checked a few documents and videos but did not understand it fully. My concern is what does the as const mean in the code below and what is the benefit of u...

I recently started working with Nest.js and its built-in unit testing library Jest, while on a task to upload a .CSV file and perform some operations on it, I decided to also unit test the endpoint...

What is the main differences between : v = t.(aType) // type assertion v = aType(t) // type conversion Where should I use type assertion or type conversion ?

I'm trying to do this: var script:HTMLScriptElement = document.getElementsByName("script")[0]; alert(script.type); but it's giving me an error: Cannot convert 'Node' to 'HTMLScriptElemen...

When asserting that a field is definitely initialized in a class, what’s the difference between ! (exclamation point, definite assignment assertion) and the declare modifier? The following code is ...

I created a new CRA project via yarn create react-app my-app --template typescript and I get the following error when running the development server (yarn start): src/App.tsx Line 5:24: Parsing er...

I'm new to the golang and I have problem while reading the nested JSON response. var d interface{} json.NewDecoder(response.Body).Decode(&d) test :=d["data"].(map[string]interface{})["type"] ...

I have created a generic data structure, with a name and a generic array in Golang. package main import "fmt" type NamedArray struct { Name string values []interface{} } func main() { data :...

I'm struggling to get the keys and values of the following interface, which is the result of JSON marshaling the result returned by Execute as demonstrated in this example: [ [ { "id": 36, "la...

How slow is using type assertions / type switches in Go, as a method of run-time type discovery? I've heard that in C/C++ for example, discovering types at run time has bad performance. To bypass ...

I just realized that it's possible to do a map lookup and a type/interface-assertion in one statement. m := map[string]interface{}{ "key": "the value", } if value, ok := m["key"].(string); ok { ...

I'm looping over data in an array and want to cast my looped item to an extended interface (it has an extra label field). What can I recast it? to a "PersonLabel"? for (const person of people) { ...

I'm new to TypeScript and I'm playing around with the various language features. Below is a code sample I've been working on during one of the many online courses. I'm having issues getting inheri...

I'm trying to achieve a type assertion by passing in a type into a function. In other words, I'm trying to achieve something like this: // Note that this is pseudocode, because Type isn't the vali...

I cracked my brain trying to make my code shorter and cleaner. The problem is in one function, that is working with different structs, that implements one interface. In some cases I need the model...

I have an array of some data which I want to map in []string. I can do it in 2 ways: a) // someData s := someData.([]string) In this case, the execution would stop after listing the error on th...

To define a map, we can do such a thing: value, present := m["key"] or: value := m["key"] and with type assertion, we can do: var i interface{} = "hello" s := i.(string) fmt.Println(s) s, ok...

Given the following code: iv, err := strconv.ParseInt("18446744073709551448", 10, 64) fmt.Println(iv) fmt.Printf("%#v\n", err) fmt.Printf("%v\n", err) //Output: 9223372036854775807 &strconv.N...

In Go, is it possible to cast variables dynamically somehow? For example, if a simple cast would be: var intAge = interfaceAge.(int) What if I do not know that age is an int in advance? A simple w...

I am studying a sample Go application that stores data in mongodb. The code at this line (https://github.com/zeebo/gostbook/blob/master/context.go#L36) seems to access a user ID stored in a g...

I am trying to type assert from a []Node, to []Symbol. In my code, Symbol implements the Node interface. Here is some surrounding code: 43 func applyLambda(args []Node, env Env) Node { 44 if le...