Meteor.js - simpl-schema issues

This might not be the best place to ask this, if not, my bad.
I’m working on XLSX to XML converter, where the uploaded file XLSX needs to have some mandatory fields, and for that validation I’m using simpl-schema.
I’ve created a Schema in an external file with all the mandatory and optional fields and on my client.js I have an array with the XLSX fields that were inputed by the user.
My objective is to validade my array against my schema, output an error if any madatory field is missing or if any field has a wrong type of input.
Here’s my code to change the input value if it’s wrong, in this case, if the input is a string “Yes” then evaluates it as true, else is false :

myField: {
        type: (Boolean), 
        optional: true,
        custom: function() {
            let a = this.value;
            if (a === "Yes") {
                return a = true;
            else { return a = false }

I’ve searched the simpl-schema docs on how to this, but I can’t manage to get it working with the examples provided, I’m stuck on this.
Sorry again if it’s the wrong place to ask this question.
Thanks in advance :raised_hand_with_fingers_splayed:

Firstly, welcome to the forums.

While we are primarily here to help people with their Free Code Camp progress, we are open to people on other paths, too. Some of what you are asking is pretty trivial in the Free Code Camp context, so you might find that if you’re not getting the instruction and material you need in your current studies, the FCC curriculum will really help you get started. At a modest guess I’d say investing a 4-5 hours working through the curriculum here will really pay off. You can find the curriculum at

With your current questions, we don’t have enough context to know what you already know or don’t know, so it is impossible to guide you without just telling you the answer (which we won’t do).

It is pretty typical on here for people to share a codepen / jsfiddle example of what they have tried so that anyone helping has more of an idea of what help is actually helpful.

Please provide some example of what you’ve tried and I’m sure you’ll get more help.

Happy coding :slight_smile:

@RandellDawson Thanks for the explanation.
I just edited the post with my code, trying to edit a value with simpl-schema.