typescript cheatsheet hints

typescriptHints.ts

// typing functions
type FocusListener = (isFocussed: boolean) => void

const addListener = (onFocusChanged: FocusListener) => {
	return true
}

// type object lietral map, can use
const cache: { [id: string]: string } = { 
  "1": "apples", 
  "2": "oranges" 
};
const recordCache: Record<number, string> = {
  1: "denis",
  2: "jane"
}


// typing try catch 
try {
    throw "Just a string"
} catch(e: any) {
    if (e instanceof Error) {
        return e.message;
    } 
    // do something with an e which is not Error
}