JSX + React 中的动态 tabIndex 属性

Question

How would I set the tabIndex attribute on a React component conditionally in the same way, say the disabled attribute is set?

I need to be able to set the value and/or remove the attribute all together.

First try was to make the entire attribute key and value a variable:

<div { tabIndex } ></div>

but the compiler complains.

Second thought was to:

const div;
if( condition ){
   div = <div tabIndex="1"></div>
}else{
   div = <div></div>
}

However, this is not desirable since my actual components have tons of attributes on them and I'd end up having large amounts of duplicate code.

My only other thought was to use a ref, then use jQuery to set the tabindex attributes, but I would rather not have to do it that way.

Any Ideas?

Answer 1

You can do it using the attribute spread operator :

let props = condition ? {tabIndex: 1} : {};
let div = <div {...props} />

Answer 2

I believe there is a simpler way (than Aaron's suggestion).

React removes an attribute from a JSX element if that attribute's value is null or undefined. I'd need this to be confirmed by someone who knows for sure.

Therefore you can use something like this:

let t1 = condition ? 1 : null;
let div = <div tabIndex={t1}>...</div>;

The tabIndex attribute will be removed if t1 is null.

Answer 3

For example, we have three attributes, tabIndex, class and id.

let tabIndex;
let id;
let className = "tab";
let props = {
    tabIndex,
    className,
    id,
}
let div = <div {...props} />

undefined/null value props will not add in div, so the render result is

<div class="tab" />