How to check isEmpty in javascript

Question

I want to check the response.data.totalRows is empty.

if (response!=undefined
   && response.data!=undefined
   && response.data.totalRows!=undefined) {

  alert(response.data.totalRows);
}

Can simplify the code?

UPDATE: it seems that there is no simple method like isEmpty(response.data.totalRows).

Answer 1

Yea, you can simply do this:

if (response && response.data && response.data.totalRows) {
    alert(response.data.totalRows);
}

In JavaScript, a object is cast to a truthy value, when used in a if. This means you can just "dump" the variable in a if or any other boolean statement, as a check to see whether or not it exists. this blog post has some more information about it.

Please note that this will not alert anything if totalRows equals 0 (since 0 is considered a falsy value.) If you also want to alert if it's 0, use this:

if (response && response.data &&
    (response.data.totalRows || response.data.totalRows === 0)) {
    alert(response.data.totalRows);
}

Or:

if (response && response.data && response.data.totalRows !== undefined) {
    alert(response.data.totalRows);
}