Cannot access ‘variable_name’ before initialization

When you assign variables using $: you cannot assign them as part of other variables declared using let, const, or var.

When you do assignments using $:, you can only use them in other variables assigned using $:. In the code posted above, you need to change the following lines:

let namesWithA = bandmembers.filter(d => {
            if (d.indexOf('a') > 0) {               
                return true;
            }
        else {
            return false
        }
    })

to the following:

$: namesWithA = bandmembers.filter(d => {
            if (d.indexOf('a') > 0) {               
                return true;
            }
        else {
            return false
        }
    })

It took me a while to figure this out and just wanted to share this with any other Svelte newbies that are starting out in this new technology.