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What is PostgreSQL explain telling me exactly?
...ple, e.g. the cost of the LIMIT is cost=0.00..3.39 and the cost of sequentially scanning post is cost=0.00..15629.12. The first number in the tuple is the startup cost and the second number is the total cost. Because I used EXPLAIN and not EXPLAIN ANALYZE, these costs are estimates, not actual measu...
How can I check for “undefined” in JavaScript? [duplicate]
...
I personally use
myVar === undefined
Warning: Please note that === is used over == and that myVar has been previously declared (not defined).
I do not like typeof myVar === "undefined". I think it is long winded and unnecessar...
What is the difference between `new Object()` and object literal notation?
...rly recognizable as to what is happening, so using new Object(), you are really just typing more and (in theory, if not optimized out by the JavaScript engine) doing an unnecessary function call.
These
person = new Object() /*You should put a semicolon here too.
It's not required, but it is goo...
Difference between Divide and Conquer Algo and Dynamic Programming
...d only once and the result of each sub-problem is stored in a table ( generally implemented as an array or a hash table) for future references. These sub-solutions may be used to obtain the original solution and the technique of storing the sub-problem solutions is known as memoization.
You may thi...
Do browsers parse javascript on every page load?
...een able to dig up. It's worth noting first that although JavaScript is usually considered to be interpreted and run on a VM, this isn't really the case with the modern interpreters, which tend to compile the source directly into machine code (with the exception of IE).
Chrome : V8 Engine
V8 has...
Pointer to class data member “::*”
...ed in pluggable architectures, but once again producing an example in a small space defeats me. The following is my best (untested) try - an Apply function that would do some pre &post processing before applying a user-selected member function to an object:
void Apply( SomeClass * c, void (Som...
Android update activity UI from service
I have a service which is checking for new task all the time. If there is new task, I want to refresh the activity UI to show that info.
I did find https://github.com/commonsguy/cw-andtutorials/tree/master/18-LocalService/ this example. Is that a good approch ? Any other examples?
...
Vertically align an image inside a div with responsive height
...
Here is a technique to align inline elements inside a parent, horizontally and vertically at the same time:
Vertical Alignment
1) In this approach, we create an inline-block (pseudo-)element as the first (or last) child of the parent, and set its height property to 100% to take all the height...
How can I easily fixup a past commit?
...xup ' workflow I asked for:
#!/usr/bin/env python
from subprocess import call
import sys
# Taken from http://stackoverflow.com/questions/377017/test-if-executable-exists-in python
def which(program):
import os
def is_exe(fpath):
return os.path.exists(fpath) and os.access(fpath, os....
What reason is there to use null instead of undefined in JavaScript?
...t undefined is always preferable and serves the same purpose programmatically. What are some practical reasons to use null instead of undefined ?
...