function change(limit) {
    var size = "";
    if (limit < 0.1 * 1024) {
        size = limit.toFixed(2) + "B"
    } else if (limit < 0.1 * 1024 * 1024) {
        size = (limit / 1024).toFixed(2) + "KB"
    } else if (limit < 0.1 * 1024 * 1024 * 1024) {
        size = (limit / (1024 * 1024)).toFixed(2) + "MB"
    } else {
        size = (limit / (1024 * 1024 * 1024)).toFixed(2) + "GB"
    }

    var sizeStr = size + "";
    var index = sizeStr.indexOf(".");
    var dou = sizeStr.substr(index + 1, 2)
    if (dou == "00") {
        return sizeStr.substring(0, index) + sizeStr.substr(index + 3, 2)
    }
    return size;
}