How to hide a component unless a condition is met?

You can use a Conditional for this. Alternatively, you can use the customConditional property to achieve this. For example, if you wish to show a button only when a specific checkbox is checked and a number that is entered is larger than 5, use the following code:

cb          = component.Checkbox("TheCheckbox", form);
cb.label    = "I agree";

nr          = component.Number("TheNumber", form);
nr.label    = "Years of experience";

btn         = component.Button("TheButton", form);
btn.hidden  = true;
btn.label   = "Continue";
btn.block   = true;
btn.customConditional = "show = data.TheCheckbox && data.TheNumber > 5;";
cb = component.Checkbox("TheCheckbox", form)
cb.label = "I agree"

nr = component.Number("TheNumber", form)
nr.label = "Years of experience"

btn = component.Button("TheButton", form)
btn.hidden = True
btn.label = "Continue"
btn.block = True
btn.customConditional = "show = data.TheCheckbox && data.TheNumber > 5;"

The resulting form in action: