Tickformat "p" fix

[etpinard]

fixes #3814 and fixes a bad commit from #3867

before: https://codepen.io/jonmmease/pen/vMMNXJ?editors=1010
after: https://codepen.io/etpinard/pen/NVpNEV?editors=1010 https://codepen.io/etpinard/pen/yWbVqd?editors=1010

cc @plotly/plotly_js

[archmoj]

@etpinard Thanks for the fix.
Unfortunately there is another issue with small ranges. See codepen where the Y-axis range is printed as 0 to 100% whereas it should be 0 to 0.01%.
Could we possibly address that in this PR?

[etpinard]

Y-axis range is printed as 0 to 100% whereas it should be 0 to 0.01%.

Oh boy. Thanks for noticing that!

[archmoj]

Y-axis range is printed as 0 to 100% whereas it should be 0 to 0.01%.

Oh boy. Thanks for noticing that!

For the funnelarea I would add the following function to the Lib. Thought it may be of interest.

lib.formatPercent = function(ratio, n) {
    n = n || 0;
    var str = (Math.round(100 * ratio * Math.pow(10, n)) * Math.pow(0.1, n)).toFixed(n) + '%';
    for(var i = 0; i < n; i++) {
        if(str.indexOf('.') !== -1) {
            str = str.replace('0%', '%');
            str = str.replace('.%', '%');
        }
    }
    return str;
};

[etpinard]

@archmoj how do you compute the n passed to your formatPercent function?

[archmoj]

@archmoj how do you compute the n passed to your formatPercent function?
That's the desired precision which in the case of financial traces is 0 or 1.
But one may pass that after calculating what precision needed or simply by using a higher default e.g. 6.

[etpinard]

I'm having second thoughts about my attempt at fixing this bug.

Closing for now.