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How to make “if not true condition”?
... then ....
OR
if (( ! $(grep -c "sysa" /etc/passwd) )) ; then ....
Finally, there is an award called the Useless Use of Cat (UUOC). :-) Some people will jump up and down and cry gothca! I'll just say that grep can take a file name on its cmd-line, so why invoke extra processes and pipe construc...
How do you reinstall an app's dependencies using npm?
Is there a simple way to reinstall all packages that my app depends on (i.e. they are in my apps node_modules folder)?
9 ...
Force browser to download image files on click
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Not fully supported in all browsers yet but it's a good solution if you don't care about IE or Safari. caniuse.com/#feat=download
– stacigh
Sep 23 '14 at 18:41
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What is the difference between a map and a dictionary?
... terms ("Object" in Javascript, "Hash" in Ruby, "Table" in Lua), but those all have separate meanings in programming too, so I'd avoid them.
See here for more info.
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How to send an email using PHP?
...d also use PHPMailer class at https://github.com/PHPMailer/PHPMailer .
It allows you to use the mail function or use an smtp server transparently. It also handles HTML based emails and attachments so you don't have to write your own implementation.
The class is stable and it is used by many other ...
How to discard local commits in Git?
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git reset --hard origin/master
will remove all commits not in origin/master where origin is the repo name and master is the name of the branch.
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A dependent property in a ReferentialConstraint is mapped to a store-generated column
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I used this query to view all the relationships in one view stackoverflow.com/questions/8094156/…
– Dave
Aug 10 '16 at 10:08
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Invoke a callback at the end of a transition
...// d3 v5
d3.select("#myid").transition().style("opacity","0").on("end", myCallback);
// old way
d3.select("#myid").transition().style("opacity","0").each("end", myCallback);
This demo uses the "end" event to chain many transitions in order.
The donut example that ships with D3 also uses this to ...
Format date to MM/dd/yyyy in JavaScript [duplicate]
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that's not actually MM/dd/yyyy. That's M/d/yyyy. Does your date need leading zeros?
– Ray Wadkins
Sep 25 '13 at 21:25
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How can I check for an empty/undefined/null string in JavaScript?
...n do
if (strValue) {
//do something
}
If you need to check specifically for an empty string over null, I would think checking against "" is your best bet, using the === operator (so that you know that it is, in fact, a string you're comparing against).
if (strValue === "") {
//...
}
...