basic javascript sortes array binary search

javascript-basic-sorted-array-binary-search.js

    var pages = [];
    var page_height= 100;
    var page_total= 2;

    for (var i = 0; i < page_total; i++) {
        var page = {min: i * page_height, max: i * page_height + page_height, page_no: i };
        pages[i] = page;
    }

    /*for loop builds something like this: var pages = [{
        min: 0,
        max: 100,
        page_no: 0
    },
    {
        min: 101,
        max: 200,
        page_no: 1
    }];*/
    
    function getPageNoByYPos(ypos, start, end) {
        var start = start || 0;
        var end = end || pages.length;
        var mid = end / 2;
        if (ypos < pages[mid].min) {
            return getPageNoByYPos(ypos, start, mid);
        } else if (ypos > pages[mid].max) {
            return getPageNoByYPos(ypos, mid, end);
        } else {
            return pages[mid];
        }
    }


    var page = getPageNoByYPos(150); // get's page two
    var my_page_no = page.page_no;