te')); return $arr; } /* 遍历用户所有主题 * @param $uid 用户ID * @param int $page 页数 * @param int $pagesize 每页记录条数 * @param bool $desc 排序方式 TRUE降序 FALSE升序 * @param string $key 返回的数组用那一列的值作为 key * @param array $col 查询哪些列 */ function thread_tid_find_by_uid($uid, $page = 1, $pagesize = 1000, $desc = TRUE, $key = 'tid', $col = array()) { if (empty($uid)) return array(); $orderby = TRUE == $desc ? -1 : 1; $arr = thread_tid__find($cond = array('uid' => $uid), array('tid' => $orderby), $page, $pagesize, $key, $col); return $arr; } // 遍历栏目下tid 支持数组 $fid = array(1,2,3) function thread_tid_find_by_fid($fid, $page = 1, $pagesize = 1000, $desc = TRUE) { if (empty($fid)) return array(); $orderby = TRUE == $desc ? -1 : 1; $arr = thread_tid__find($cond = array('fid' => $fid), array('tid' => $orderby), $page, $pagesize, 'tid', array('tid', 'verify_date')); return $arr; } function thread_tid_delete($tid) { if (empty($tid)) return FALSE; $r = thread_tid__delete(array('tid' => $tid)); return $r; } function thread_tid_count() { $n = thread_tid__count(); return $n; } // 统计用户主题数 大数量下严谨使用非主键统计 function thread_uid_count($uid) { $n = thread_tid__count(array('uid' => $uid)); return $n; } // 统计栏目主题数 大数量下严谨使用非主键统计 function thread_fid_count($fid) { $n = thread_tid__count(array('fid' => $fid)); return $n; } ?>html - javascript: does onsubmit only execute when it detects a "return false"- Stack Overflow

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    i dont quite understand how the onsubmit="return validate()" works. why do i have to return the function? does this work only when it detects a return false from the statement?

    <script type="text/javascript">
    function validate() {
        if ((document.example2.naming.value == "") || (document.example2.feed.value == "")) {
            alert("You must fill in all of the required .fields!");
            return false;
        }
        else {
            return true;
        }
</script>

<form name="example2" onsubmit="return validate()">
<input type="submit" name="B1" value="Submit">​​​​​​​

    i dont quite understand how the onsubmit="return validate()" works. why do i have to return the function? does this work only when it detects a return false from the statement?

    <script type="text/javascript">
    function validate() {
        if ((document.example2.naming.value == "") || (document.example2.feed.value == "")) {
            alert("You must fill in all of the required .fields!");
            return false;
        }
        else {
            return true;
        }
</script>

<form name="example2" onsubmit="return validate()">
<input type="submit" name="B1" value="Submit">​​​​​​​
    • javascript
    • html
    Share Improve this question edited Sep 16, 2012 at 17:49 A.M.K 16.8k4 gold badges35 silver badges64 bronze badges asked Sep 16, 2012 at 17:27 user1666411user1666411 3352 gold badges7 silver badges11 bronze badges 1
    • Check your assumptions again. – user166390 Commented Sep 16, 2012 at 17:30
    Add a ment  | 

    2 Answers 2

    Reset to default 13

    Using return for onsubmit determines whether the form actually submits or not (true or false, respectively). This is useful for Javascript when you want to do something specific before allowing the form to submit or not. For example, like the code you provided, the point is to stop the form from submitting if the form isn't valid - if a certain field is blank. The important part is that you need to include return in the onsubmit part, as well as actually returning true or false in the function you call. This is because the behavior for onsubmit is to always plete unless you return false. So when you do something like:

    onsubmit="validate();"

    nothing is returned (because of the lack of return) - so the function is run but that's it, so the form is submitted. When you add return, then the submitting depends on the return value - what's returned from the function. If you don't use return, it doesn't matter what the validate function returns, because the result of validate is not actually returned to onsubmit.

    When returning false, you prevent the form from being submitted. Otherwise, the form would be submitted, even though it may have validation errors, e.g., the feed value was empty.

    On the other hand, if you return true, the form data will be submitted to the URL defined by the action attribute.

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