Reason For New Answer
Vanilla Javascript is necessary for a lot of people in 2018. As a lot of frameworks and Javascript libraries that exist today do not play well with jQuery. Once upon a time answering all Javascript problems with a jQuery solution was acceptable but it is no longer feasible.
Problem
When loading C3.js or D3.js graphs, if the viewport is not actively in site during page load the graphs do not render correctly.
Example
If you type in the URL then open a new tab and then go back after your page loads.
If you refresh the page that has your graphs on it then minimize the browser and open it back up after the page has loaded.
If you refresh or go to the page with the graphs then swipe away to a new window on your computer. Then go back to the page with the graphs after they have loaded.
In all these cases your C3.js / D3.js graphs will not render correctly. Typically you will see a blank canvas. So if you were expecting a bar chart, you would see a canvas without the bars being drawn.
Background
Although I have seen this question answered I needed an answer that did NOT use jQuery. Now that we have reached the days of everything can not be fixed with jQuery I thought it seemed fit to provide a vanilla Javascript answer to this question.
My team faced the issue that the C3.js / D3.js graphs would not load if you refreshed the page and swiped away or minimized. Basically if you did not stay on the page and keep it in site till it was done loading you would not see the graphs till you resized the page again. I know this is a problem that happens to everyone using C3.js / D3.js but we are specifically using Lightning in Salesforce.
Answer
Our fix was to add this in the controller function that initializes the charts. Anyone can use this in any function they write to initialize their C3.js / D3.js graphs regardless of their stack. This is not Salesforce dependent but it does indeed work if you are facing this issue in Salesforce.
document.addEventListener('visibilitychange', () => {
console.log(document.visibilityState);
window.dispatchEvent(new Event('resize'));
});