Loading failed on some pages due to using mixed content (HTTP and HTTPS). This uses HTTPS to load all of the D3 library scripts so that we don't have to worry about accessing the page over HTTPS failing out sometimes.
Another option would've been to use //d3js.org/d3.v4.js instead of https://d3js.org/d3.v4.js and let the browser use the protocol the page initially loaded with to fix this.
Loading failed on some pages due to using mixed content (HTTP and HTTPS). This uses HTTPS to load all of the D3 library scripts so that we don't have to worry about accessing the page over HTTPS failing out sometimes.
Another option would've been to use //d3js.org/d3.v4.js instead of https://d3js.org/d3.v4.js and let the browser use the protocol the page initially loaded with to fix this.