How to know if an array is Empty?

Question

I'm passing an array from an API and want to know if the array is empty, to print an error message.

Look at different sites and none of them were working.

 {this.props.items ? errorMessage : <h1>Working</h1>}

• Engineer: Possible duplicate of How can I check whether an array is null / empty?

Answer 1

You can use length property

 {this.props.items.length == 0 ? errorMessage : <h1>Working</h1>}

• Idan: @Martin hah for you i can replace to "up arrow"

Answer 2

this.props.items && this.props.items.length > 0 ? <h1>Working</h1> : errorMessage

Answer 3

Fist check weather Array exists or not then check the length of Array greater than 0, always use double negations to convert that array into bool type

{!!this.props.items && this.props.items.length > 0 ? <h1>Working</h1> : errorMessage}

Answer 4

Check the lodash library. It's very helpful for that kind of needs.

https://lodash.com/docs/4.17.15#isEmpty

With this you could just use:

{isEmpty(this.props.items) ? errorMessage: <h1>Working</h1>}

Answer 5

Safer to check with the type before checking its length, as type string can return length as well

{ Array.isArray(this.props.items) && this.props.items.length < 1 ? errorMessage : <h1>Working</h1> }