dl_txns.js

function download_txns(name, txns) {
    let b = new Uint8Array(0);
    for(const txn in txns){
        b = concatTypedArrays(b, txns[txn])
    }
    var blob = new Blob([b], {type: "application/octet-stream"});

    var link = document.createElement('a');
    link.href = window.URL.createObjectURL(blob);
    link.download = name;
    link.click();
}

function concatTypedArrays(a, b) {
    var c = new (a.constructor)(a.length + b.length);
    c.set(a, 0);
    c.set(b, a.length);
    return c;
}