for stackowerflow

var someVar = 50;


function someStupidFunction() {
    if (objJson.length > 50) {
        document.getElementById("nextPage").style.visibility = "visible";
    }

    if (someVar <= 50) {
        document.getElementById("prevPage").style.visibility ="hidden";
    } else {
        document.getElementById("prevPage").style.visibility = "visible";
    }
}


function nextPage() {
    document.getElementById("listingTable").innerHTML = "";

    if (someVar < objJson.length) {
        document.getElementById("nextPage").style.visibility = "visible";
    } else {
        document.getElementById("nextPage").style.visibility = "hidden";
    }

    for (var i = someVar - 50; i < someVar; i++) {
        document.getElementById("listingTable").innerHTML += objJson[i].adName + "<br>";
    }

    someVar += 50;

    document.getElementById("prevPage").style.visibility = "visible";
}


function prevPage() {
    document.getElementById("listingTable").innerHTML = "";

    if (someVar > 50) {
        document.getElementById("prevPage").style.visibility = "visible";
    } else {
        document.getElementById("prevPage").style.visibility = "hidden";
    }

    for (var i = someVar - 50; i < someVar; i++) {
        document.getElementById("listingTable").innerHTML += objJson[i].adName + "<br>";
    }

    someVar -= 50;

    document.getElementById("nextPage").style.visibility = "visible";
}