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What is the difference between JSON and Object Literal Notation?
...ring
a number
an (JSON) object
an array
true
false
null
Duplicate keys ({"foo":"bar","foo":"baz"}) produce undefined, implementation-specific results; the JSON specification specifically does not define their semantics
In JavaScript, object literals can have
String literals, number literals or ...
Using parameters in batch files at Windows command line
...e for a real-life utility.
Let us say that we want to implement a utility foobar. It requires an initial command. It has an optional parameter --foo which takes an optional value (which cannot be another parameter, of course); if the value is missing it defaults to default. It also has an optional ...
C++ stl stack/queue 的使用方法 - C/C++ - 清泛网 - 专注C/C++及内核技术
...x 出队，反之，则将y 排在x 前面，x 将先出队。
看下面这个简单的示例：
#include <iostream>
#include <queue>
using namespace std;
class T
{
public:
int x, y, z;
T(int a, int b, int c):x(a), y(b), z(c)
{
}
};
bool operator < (const T &...
How to declare string constants in JavaScript? [duplicate]
...m = { //not really an enum, just an object that serves a similar purpose
FOO : "foofoo",
BAR : "barbar",
}
You can now print out 'foofoo' with
jsEnum.FOO
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...
Is it possible to implement dynamic getters/setters in JavaScript?
...ew Error("This browser doesn't support Proxy");
}
let original = {
"foo": "bar"
};
let proxy = new Proxy(original, {
get(target, name, receiver) {
let rv = Reflect.get(target, name, receiver);
if (typeof rv === "string") {
rv = rv.toUpperCase();
...
jQuery Determine if a matched class has a given id
...rget all elements with a given id, that also have a particular class:
$("#foo.bar"); // Matches <div id="foo" class="bar">
This should look similar to something you'd write in CSS. Note that it won't apply to all #foo elements (though there should only be one), and it won't apply to all .ba...
Using braces with dynamic variable names in PHP
...he examples below show how the order of evaluation has changed.
Case 1 : $$foo['bar']['baz']
PHP5 interpetation : ${$foo['bar']['baz']}
PHP7 interpetation : ${$foo}['bar']['baz']
Case 2 : $foo->$bar['baz']
PHP5 interpetation : $foo->{$bar['baz']}
PHP7 interpetation : $foo->{$bar}['baz']
...
Get array of object's keys
...
Use Object.keys:
var foo = {
'alpha': 'puffin',
'beta': 'beagle'
};
var keys = Object.keys(foo);
console.log(keys) // ['alpha', 'beta']
// (or maybe some other order, keys are unordered).
This is an ES5 feature. This means it ...
PHP abstract properties
...checks (say, in the constructor) for the $tablename variable, e.g.:
class Foo_Abstract {
public final function __construct(/*whatever*/) {
if(!isset($this->tablename))
throw new LogicException(get_class($this) . ' must have a $tablename');
}
}
To enforce this for all derived clas...
What is your single most favorite command-line trick using Bash? [closed]
...
Renaming/moving files with suffixes quickly:
cp /home/foo/realllylongname.cpp{,-old}
This expands to:
cp /home/foo/realllylongname.cpp /home/foo/realllylongname.cpp-old
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