D3: Formatting tick value. To show B (Billion) instead of G (Giga)

If you like the formatting of SI-prefix, but not the actual prefix, just swap it out with a simple .replace:

var f = d3.format("0.2s");

document.write(
  f(1e9).replace(/G/,"B")
);

<script src="https://d3js.org/d3.v4.min.js"></script>

If you want to apply Mark's Answer Globally, I used the following

fcopy = d3.format;
function myFormat(){ 
         function_ret = fcopy.apply(d3, arguments) 
         return (function(args){return function (){ 
                return args.apply(d3, arguments).replace(/G/, "B");
         }})(function_ret) 
} 
d3.format = myFormat;

I had the same problem with Superset, I added this in the static/dashboard file.