以下のコードで、指定された形式のいずれかで日付の検証を実行して、開始/開始日と終了/終了日を検証できるようにします。いくつかのより良いアプローチがあるかもしれませんが、これは思いつきました。提供される日付形式と日付文字列は密接に関連しています。
<script type="text/javascript">
    function validate() {
        var format = 'yyyy-MM-dd';
        if(isAfterCurrentDate(document.getElementById('start').value, format)) {
            alert('Date is after the current date.');
        } else {
            alert('Date is not after the current date.');
        }
        if(isBeforeCurrentDate(document.getElementById('start').value, format)) {
            alert('Date is before current date.');
        } else {
            alert('Date is not before current date.');
        }
        if(isCurrentDate(document.getElementById('start').value, format)) {
            alert('Date is current date.');
        } else {
            alert('Date is not a current date.');
        }
        if (isBefore(document.getElementById('start').value, document.getElementById('end').value, format)) {
            alert('Start/Effective Date cannot be greater than End/Expiration Date');
        } else {
            alert('Valid dates...');
        }
        if (isAfter(document.getElementById('start').value, document.getElementById('end').value, format)) {
            alert('End/Expiration Date cannot be less than Start/Effective Date');
        } else {
            alert('Valid dates...');
        }
        if (isEquals(document.getElementById('start').value, document.getElementById('end').value, format)) {
            alert('Dates are equals...');
        } else {
            alert('Dates are not equals...');
        }
        if (isDate(document.getElementById('start').value, format)) {
            alert('Is valid date...');
        } else {
            alert('Is invalid date...');
        }
    }
    /**
     * This method gets the year index from the supplied format
     */
    function getYearIndex(format) {
        var tokens = splitDateFormat(format);
        if (tokens[0] === 'YYYY'
                || tokens[0] === 'yyyy') {
            return 0;
        } else if (tokens[1]=== 'YYYY'
                || tokens[1] === 'yyyy') {
            return 1;
        } else if (tokens[2] === 'YYYY'
                || tokens[2] === 'yyyy') {
            return 2;
        }
        // Returning the default value as -1
        return -1;
    }
    /**
     * This method returns the year string located at the supplied index
     */
    function getYear(date, index) {
        var tokens = splitDateFormat(date);
        return tokens[index];
    }
    /**
     * This method gets the month index from the supplied format
     */
    function getMonthIndex(format) {
        var tokens = splitDateFormat(format);
        if (tokens[0] === 'MM'
                || tokens[0] === 'mm') {
            return 0;
        } else if (tokens[1] === 'MM'
                || tokens[1] === 'mm') {
            return 1;
        } else if (tokens[2] === 'MM'
                || tokens[2] === 'mm') {
            return 2;
        }
        // Returning the default value as -1
        return -1;
    }
    /**
     * This method returns the month string located at the supplied index
     */
    function getMonth(date, index) {
        var tokens = splitDateFormat(date);
        return tokens[index];
    }
    /**
     * This method gets the date index from the supplied format
     */
    function getDateIndex(format) {
        var tokens = splitDateFormat(format);
        if (tokens[0] === 'DD'
                || tokens[0] === 'dd') {
            return 0;
        } else if (tokens[1] === 'DD'
                || tokens[1] === 'dd') {
            return 1;
        } else if (tokens[2] === 'DD'
                || tokens[2] === 'dd') {
            return 2;
        }
        // Returning the default value as -1
        return -1;
    }
    /**
     * This method returns the date string located at the supplied index
     */
    function getDate(date, index) {
        var tokens = splitDateFormat(date);
        return tokens[index];
    }
    /**
     * This method returns true if date1 is before date2 else return false
     */
    function isBefore(date1, date2, format) {
        // Validating if date1 date is greater than the date2 date
        if (new Date(getYear(date1, getYearIndex(format)), 
                getMonth(date1, getMonthIndex(format)) - 1, 
                getDate(date1, getDateIndex(format))).getTime()
            > new Date(getYear(date2, getYearIndex(format)), 
                getMonth(date2, getMonthIndex(format)) - 1, 
                getDate(date2, getDateIndex(format))).getTime()) {
            return true;
        } 
        return false;                
    }
    /**
     * This method returns true if date1 is after date2 else return false
     */
    function isAfter(date1, date2, format) {
        // Validating if date2 date is less than the date1 date
        if (new Date(getYear(date2, getYearIndex(format)), 
                getMonth(date2, getMonthIndex(format)) - 1, 
                getDate(date2, getDateIndex(format))).getTime()
            < new Date(getYear(date1, getYearIndex(format)), 
                getMonth(date1, getMonthIndex(format)) - 1, 
                getDate(date1, getDateIndex(format))).getTime()
            ) {
            return true;
        } 
        return false;                
    }
    /**
     * This method returns true if date1 is equals to date2 else return false
     */
    function isEquals(date1, date2, format) {
        // Validating if date1 date is equals to the date2 date
        if (new Date(getYear(date1, getYearIndex(format)), 
                getMonth(date1, getMonthIndex(format)) - 1, 
                getDate(date1, getDateIndex(format))).getTime()
            === new Date(getYear(date2, getYearIndex(format)), 
                getMonth(date2, getMonthIndex(format)) - 1, 
                getDate(date2, getDateIndex(format))).getTime()) {
            return true;
        } 
        return false;
    }
    /**
     * This method validates and returns true if the supplied date is 
     * equals to the current date.
     */
    function isCurrentDate(date, format) {
        // Validating if the supplied date is the current date
        if (new Date(getYear(date, getYearIndex(format)), 
                getMonth(date, getMonthIndex(format)) - 1, 
                getDate(date, getDateIndex(format))).getTime()
            === new Date(new Date().getFullYear(), 
                    new Date().getMonth(), 
                    new Date().getDate()).getTime()) {
            return true;
        } 
        return false;                
    }
    /**
     * This method validates and returns true if the supplied date value 
     * is before the current date.
     */
    function isBeforeCurrentDate(date, format) {
        // Validating if the supplied date is before the current date
        if (new Date(getYear(date, getYearIndex(format)), 
                getMonth(date, getMonthIndex(format)) - 1, 
                getDate(date, getDateIndex(format))).getTime()
            < new Date(new Date().getFullYear(), 
                    new Date().getMonth(), 
                    new Date().getDate()).getTime()) {
            return true;
        } 
        return false;                
    }
    /**
     * This method validates and returns true if the supplied date value 
     * is after the current date.
     */
    function isAfterCurrentDate(date, format) {
        // Validating if the supplied date is before the current date
        if (new Date(getYear(date, getYearIndex(format)), 
                getMonth(date, getMonthIndex(format)) - 1, 
                getDate(date, getDateIndex(format))).getTime()
            > new Date(new Date().getFullYear(),
                    new Date().getMonth(), 
                    new Date().getDate()).getTime()) {
            return true;
        } 
        return false;                
    }
    /**
     * This method splits the supplied date OR format based 
     * on non alpha numeric characters in the supplied string.
     */
    function splitDateFormat(dateFormat) {
        // Spliting the supplied string based on non characters
        return dateFormat.split(/\W/);
    }
    /*
     * This method validates if the supplied value is a valid date.
     */
    function isDate(date, format) {                
        // Validating if the supplied date string is valid and not a NaN (Not a Number)
        if (!isNaN(new Date(getYear(date, getYearIndex(format)), 
                getMonth(date, getMonthIndex(format)) - 1, 
                getDate(date, getDateIndex(format))))) {                    
            return true;
        } 
        return false;                                      
    }
</script>
以下はHTMLスニペットです
<input type="text" name="start" id="start" size="10" value="" />
<br/>
<input type="text" name="end" id="end" size="10" value="" />
<br/>
<input type="button" value="Submit" onclick="javascript:validate();" />
               
              
{}ツールバーボタンでソースコードをフォーマットできます。今回はあなたのためにそれをしました。また、あなたの問題に関するいくつかの情報を提供しよう:作業しない記述はとして有用であるし、それを修正するソリューション。