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How to check for an undefined or null variable in JavaScript?

... @SharjeelAhmed It is mathematically corrected. NaN from difference equation can never expected to be equal – Thaina Oct 4 '19 at 4:12 ...
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Different ways of adding to Dictionary

...if it does and the parameter add is true, it throws the exception. So for all purposes and intents the performance is the same. Like a few other mentions, it's all about whether you need the check, for attempts at adding the same key twice. Sorry for the lengthy post, I hope it's okay. ...
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Create directory if it does not exist

... What will -Force actually do? The documentation says "Forces this cmdlet to create an item that writes over an existing read-only item". Will it delete an existing folder? It should be clear in this answer. – Peter Mortensen...
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How can I use Timer (formerly NSTimer) in Swift?

...ctor(eventWith(timer:)), userInfo: [ "foo" : "bar" ], repeats: true) } // Timer expects @objc selector @objc func eventWith(timer: Timer!) { let info = timer.userInfo as Any print(info) } } ...
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Casting to string in JavaScript

... searched for those three options in the jQuery source code, and they are all in use . I would like to know if there are any differences between them: ...
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Why does this loop produce “warning: iteration 3u invokes undefined behavior” and output more than 4

... If during the evaluation of an expression, the result is not mathematically defined or not in the range of representable values for its type, the behavior is undefined. [ Note: most existing implementations of C++ ignore integer overflows. Treatment of division by zero, forming a remainde...
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How do I merge two javascript objects together in ES6+?

.../en-US/docs/Web/JavaScript/Reference/… Running babel-node: const ob1 = {foo: 123}; const ob2 = {bar: 234}; const merged = {...ob1, ...ob2}; console.log(merged) Output: { foo: 123, bar: 234 } – Thijs Koerselman Sep 4 '15 at 18:52 ...
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Mockito How to mock only the call of a method of the superclass

...ad of extending a super class the problem is gone. If however you are not allowed to change the code, but you must test it anyway, and in this awkward way, there is still hope. With some AOP tools (for example AspectJ) you can weave code into the super class method and avoid its execution entirely ...
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How to print a debug log?

... +1 It took me too long to find this answer. This is all I really was looking for. I couldn't figure out how to see what my array contained (working in Drupal). – SteveS May 7 '14 at 14:31 ...
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AngularJS directive with default options

...from the template. If you're passing an array f.e. it should be attributes.foo = '["one", "two", "three"]' instead of attributes.foo = ["one", "two", "three"] – Dominik Ehrenberg Apr 22 '15 at 7:39 ...