Gfast2
/ usingTypeParametersInTypeConstrain.ts
Created
March 24, 2020 07:56
You can declare a type parameter that is constrained by another type parameter. For example, here we’d like to get a property from an object given its name. We’d like to ensure that we’re not accidentally grabbing a property that does not exist on the obj, so we’ll place a constraint between the two types:
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| // https://www.typescriptlang.org/docs/handbook/generics.html | |
| function getProperty<T, K extends keyof T>(obj: T, key: K) { | |
| return obj[key]; | |
| } | |
| let x = { a: 1, b: 2, c: 3, d: 4 }; | |
| getProperty(x, "a"); // okay | |
| getProperty(x, "m"); // error: Argument of type 'm' isn't assignable to 'a' | 'b' | 'c' | 'd'. |
Gfast2
/ ReactComponentSizing.tsx
Created
May 15, 2020 08:47
A Way to read a react component size with resize eventhandler
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| class DivSize extends React.Component { | |
| constructor(props) { | |
| super(props) | |
| this.state = { | |
| width: 0 | |
| } | |
| this.resizeHandler = this.resizeHandler.bind(this); | |
| } |
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