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How do I check if an object has a key in JavaScript? [duplicate]
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Try the JavaScript in operator.
if ('key' in myObj)
And the inverse.
if (!('key' in myObj))
Be careful! The in operator matches all object keys, including those in the object's prototype chain.
Use myObj.hasOwnProperty('key') to check an object's own ...
What's the use of do while(0) when we define a macro? [duplicate]
...emicolon and make it look and act more like a function.
It also works with if/else clauses properly then.
Without the while(0), your code above would not work with
if (doit)
INIT_LIST_HEAD(x);
else
displayError(x);
since the semicolon after the macro would "eat" the else clause, and the...
How can I capture the right-click event in JavaScript? [duplicate]
...et to return false, otherwise the standard context menu will still pop up.
If you are going to use a function you've written rather than javascript:alert("Success!"), remember to return false in BOTH the function AND the oncontextmenu attribute.
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CREATE TABLE IF NOT EXISTS equivalent in SQL Server [duplicate]
CREATE TABLE IF NOT EXISTS works on mysql but fails with SQL Server 2008 R2.
What is the equivalent syntax?
1 Answer
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Testing for empty or nil-value string [duplicate]
I'm trying to set a variable conditionally in Ruby. I need to set it if the variable is nil or empty (0 length string). I've come up with the following:
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Python 'If not' syntax [duplicate]
I'm a bit confused about how/why so many python developers use if not in their conditional statements.
1 Answer
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python if 语句只执行代码块中的第一行？ - 更多技术 - 清泛网 - 专注C/C++及内核技术
python if 语句只执行代码块中的第一行？极有可能是因为if后的第一行代码到第二行代码中间是空格而非Tab，导致第二行被认为是新的执行分支，因此if的代码块范围仅第一句。将第二行代码前面的空格换成Tab键即可解决。极有可...
Android: How can I get the current foreground activity (from a service)?
...e activity, with a low-priority BroadcastReceiver as backup (to raise a Notification if the activity is not on-screen) -- here is a blog post with more on this pattern
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Flatten an irregular list of lists
...boost the performance.
Python 2
def flatten(l):
for el in l:
if isinstance(el, collections.Iterable) and not isinstance(el, basestring):
for sub in flatten(el):
yield sub
else:
yield el
I used the Iterable ABC added in 2.6.
Python 3
I...
How to use protractor to check if an element is visible?
I'm trying to test if an element is visible using protractor. Here's what the element looks like:
8 Answers
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