I’m using math.js to calculate a simple addition formula…

I want the total of several input fields to display:

http://www.screencast.com/t/D1wmmKI8

The problem I have is that the total of all fields being added does not appear until a number has been entered in each field.

Instead, I want the total to be calculated, even if a field is left blank.

My limited understanding is that I need to use an array expression instead.

In Bubble, this is the current expression I am using for simple addition: http://www.screencast.com/t/u3MCkUKChh

I don’t know what syntax I need to use to calculate an array. (The documentation in math.js is too cryptic for me to understand).