open={Boolean(anchor)} 对 MUI 组件意味着什么

Question

Working with some legacy code where a MUI menu has been defined within a React component written with TypeScript as below:

interface Props {
anchor: HTMLButtonElement | null;
}
...
<Menu
  id="order-menu"
  anchorEl={anchor}
  open={Boolean(anchor)}
  onClose={onClose}
>
...
</Menu>

Not sure if I understand the meaning or purpose of the syntax open={Boolean(anchor)} . It would be kind if anyone can explain a bit.

Answer 1

Boolean(...) returns a boolean value, ie true or false .

If anchor is truthy (ie there's an object), then Boolean(anchor) returns true .

If anchor is falsy (eg it's null ), then Boolean(anchor) returns false .

In your code snippet, it means that Menu prop open will be set to true if anchor is an object, and false if there's no object (if anchor is null ).

Answer 2

Syntax open={Boolean(anchor)} refers to whether your Menu will open/close as the type of open props is Boolean. And here Boolean(anchor) type converting is used to convert anchor value in to Boolean value.

So when you set anchor value as like event.target.value or ref based then Boolean(anchor) === true But when you reset the anchor value like null or undefined then Boolean(anchor) === false

So based on that your Menu Element open/close