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; } ?>allow zero (0) in if checking javascript - Stack Overflow

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    allow zero (0) in if checking javascript - Stack Overflow

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    I use present or not as flag then perform relevant action. Like in my case I do something with stock or grade or both. Guess what is the problem?

    stock = parseInt(req.body.stock),
grade = parseInt(req.body.grade),

var update = {};

if(stock){
  update = {'data.$.stock':stock}
}

if(grade){
  update = {'data.$.grade':grade}
}

if(stock && grade){
  update = {
    'data.$.grade':grade,
    'data.$.stock':stock
  }
}

    There will be a bug if stock 0 is allowed in this case. So if inventory is zero, the bug will occur. Because it doesn't pass if(stock){}, hmm how to resolve this?

    I don't want to write if stock is not undefined && stock is not null, that's too long.

    I use present or not as flag then perform relevant action. Like in my case I do something with stock or grade or both. Guess what is the problem?

    stock = parseInt(req.body.stock),
grade = parseInt(req.body.grade),

var update = {};

if(stock){
  update = {'data.$.stock':stock}
}

if(grade){
  update = {'data.$.grade':grade}
}

if(stock && grade){
  update = {
    'data.$.grade':grade,
    'data.$.stock':stock
  }
}

    There will be a bug if stock 0 is allowed in this case. So if inventory is zero, the bug will occur. Because it doesn't pass if(stock){}, hmm how to resolve this?

    I don't want to write if stock is not undefined && stock is not null, that's too long.

    • javascript
    Share Improve this question asked Jan 2, 2017 at 17:19 Thian Kian PhinThian Kian Phin 9313 gold badges13 silver badges27 bronze badges 4
    • 2 if (stock == null) will be true when stock is either null or undefined. – Pointy Commented Jan 2, 2017 at 17:20
    • 1 stock will never even be undefined or null it will either be a number or NaN. – VLAZ Commented Jan 2, 2017 at 17:20
    • 2 "I don't want to write if stock is not undefined && stock is not null, that's too long." That's an odd reason, considering you were willing to write 20x that in your question here. – ceejayoz Commented Jan 2, 2017 at 17:20
    • 1 Too long? Too bad. Either stop using undefined the way you're using it, or deal with the fallout :) – Luaan Commented Jan 2, 2017 at 17:21
    Add a ment  | 

    3 Answers 3

    Reset to default 7

    You could simplify the code by assigning to a property, instead of assigning a whole object.

    stock = parseInt(req.body.stock, 10), // use radix as well
grade = parseInt(req.body.grade, 10),

var update = {};

if (stock >= 0) { 
    update['data.$.stock'] = stock; // set property
}

if (grade >= 0) {
    update['data.$.grade'] = grade; // set property
}

// skip part for assigning both

    You could use isNaN(). Like

    if (!isNaN(stock))

    https://developer.mozilla/en/docs/Web/JavaScript/Reference/Global_Objects/isNaN

    Simply pare stock being greater than or equal to 0:

    if (stock >= 0)

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