nagi1 / hill-chart

var jumpToCode = (function init() {

    // Classes of code we would like to highlight in the file view

    var missingCoverageClasses = ['.cbranch-no', '.cstat-no', '.fstat-no'];

    // Elements to highlight in the file listing view

    var fileListingElements = ['td.pct.low'];

    // We don't want to select elements that are direct descendants of another match

    var notSelector = ':not(' + missingCoverageClasses.join('):not(') + ') > '; // becomes `:not(a):not(b) > `

    // Selecter that finds elements on the page to which we can jump

    var selector =

        fileListingElements.join(', ') +

        ', ' +

        notSelector +

        missingCoverageClasses.join(', ' + notSelector); // becomes `:not(a):not(b) > a, :not(a):not(b) > b`

    // The NodeList of matching elements

    var missingCoverageElements = document.querySelectorAll(selector);

    var currentIndex;

    function toggleClass(index) {

        missingCoverageElements

            .item(currentIndex)

            .classList.remove('highlighted');

        missingCoverageElements.item(index).classList.add('highlighted');

    }

    function makeCurrent(index) {

        toggleClass(index);

        currentIndex = index;

        missingCoverageElements.item(index).scrollIntoView({

            behavior: 'smooth',

            block: 'center',

            inline: 'center'

        });

    }

    function goToPrevious() {

        var nextIndex = 0;

        if (typeof currentIndex !== 'number' || currentIndex === 0) {

            nextIndex = missingCoverageElements.length - 1;

        } else if (missingCoverageElements.length > 1) {

            nextIndex = currentIndex - 1;

        }

        makeCurrent(nextIndex);

    }

    function goToNext() {

        var nextIndex = 0;

        if (

            typeof currentIndex === 'number' &&

            currentIndex < missingCoverageElements.length - 1

        ) {

            nextIndex = currentIndex + 1;

        }

        makeCurrent(nextIndex);

    }

    return function jump(event) {

        switch (event.which) {

            case 78: // n

            case 74: // j

                goToNext();

                break;

            case 66: // b

            case 75: // k

            case 80: // p

                goToPrevious();

                break;

        }

    };

})();

window.addEventListener('keydown', jumpToCode);