How do I return a Float32Array from a function? [duplicate]

I am trying to compartmentalize JavaScript code. I am using a Float32Array so I can use the .map() function. When I put the code that builds the array from a file in another function, how do I ensure that the datatype is returned/recognized?

var secondsArray = new Float32Array(); secondsArray = SomeFunction() ; secondsArray.map((start_time,index) => //more code

exception: secondsArry.map is not a function

The function:

async function SomeFunction() { // some stuff secondsArray = new Float32Array(timeArray.length-1); return secondsArray; }