i have a property like this “data.property” = “16165456”.. i try to create a object like this i use split and and loop but not work Answer A few issues: currentObject[part] = currentObject[part] is a statement that accomplishes nothing. You’d want to indicate what to assign when that property does not yet exist, so do: this.currentObject is a property, and
Tag: types
How do I type-check this object in Typescript
I am in a state of confusion on how I would go about type-checking this variable, but I am not able to do it. What I understand is that this is an object which contains fields, but these fields are written in a obscure way. The object is called userApproval Here is the object when I output it to console.
Typescript concat two data types array in one
How do I concat two types array in one array using concat. If I initialize it with two data types it works fine but when I concat it. Typescript throws an error that both types are incompatible. Answer I think it has to do with the implementation of .concat() in Typescript. It is implemented as the type of the merged
How to create a new generic object type that uses react-navigation’s generics?
In my React Native project I have multiple screens, every screen I have to import these types and set is as props type in my screen over and over again. Can it be more be simplified into like this? So from that I can only import one type only Answer The React Navigation lib offers a generic type already for
Is it possible to define new data types in JavaScript?
MDN says there are nine data types in latest JS spec. I wondering if these are the only nine data types that the spec allows programmers to use. Just to clarify, I think programmer-defined functions/constructors internally using prototypical inheritance are still Objects, so do not qualify as new data types. Answer There is no facility that allows defining custom core
Stale closures with react hooks and click events
I have created a codesandbox for easier debugging: https://codesandbox.io/s/hardcore-dirac-nh4iz?file=/src/App.tsx I have built a DataList component that I use like: All of the functionality is handled inside of a useListBox hook, which includes taking the onSelect prop from each child and binding that to a click event on the List itself. However, a stale closure is preventing the count value from
Typescript map string literal types to uppercase
I would like to have a type b like So I tried But that does not do what I want it to do. Thank you for reading 🙂 Answer You can now do this with the introduction of Template Literal Types: TS Playground In addition to Uppercase<StringType>, there are also the following helper types: Lowercase Capitalize Uncapitalize They can be
Why does Javascript only type-cast for string concatenation on strings that are already assigned?
I noticed something strange when messing around with strings and numbers in a Javascript console. Doing this: “$99.9” += 0 causes SyntaxError: Invalid left-hand side in assignment. But if I assign the string to a variable, the behavior is different (and more in line with what we’ve come to expect/accept from Javascript) let str = “$99.9” str += 0 //
How do I add TypeScript types to a JavaScript module without switching to TypeScript?
I guess the title is somewhat confusing, but I wasn’t able to put it in a more concise way in a short title. However, this is what I want to do: I have an npm module that is written in JavaScript, not TypeScript. Some of the users of this module are using TypeScript, so it would be nice if I
Why does TypeScript use “Like” types?
Why does TypeScript have a type and then a “like type”? An example of this is Promise<T> and PromiseLike<T>. What are the differences between these two types? When should I use them? In this case why not just have one Promise type? Answer If you look at the definition files (let’s take lib.es6.d.ts) then it’s pretty straight forward. For example