JavaScript code snippets _ javascript tips-js tutorials

Record the code snippet that I have to like after seeing it. The content of this clipboard will be updated constantly. Please pay attention to the Dynamic Construction of regular expressions.

The Code is as follows:

New RegExp (Expr. match [type]. source + (/(?! [^ \ [] * \]) (?! [^ \ (] * \)/. Source ))

This avoids character escaping when a regular expression is dynamically constructed from sizzle.

More flexible and clever digital Zeros

The Code is as follows:

Function prefixInteger (num, length ){
Return (num/Math. pow (10, length). toFixed (length). substr (2 );
}

Returns the maximum and minimum values of an array.

The Code is as follows:

Math. max. apply (Math, [1, 2, 3]) // 3
Math. min. apply (Math, [1, 2, 3]) // 1

Generate beautiful random strings

The Code is as follows:

Math. random (). toString (16). substring (2); // 8 digits
Math. random (). toString (36). substring (2); // 16 digits

Get Timestamp

Relative
Var timeStamp = (new Date). getTime ();
The following method is more convenient:

The Code is as follows:

Var timeStamp = Number (new Date );

Convert to a value and take an integer

The Code is as follows:

Var result = '3. 1415926 '| 0; // 3

String formatting

The Code is as follows:

Function format (format ){
If (! FB. String. format. _ formatRE ){
FB. String. format. _ formatRE =/(\ {[^ \} ^ \ {] + \})/g;
}

Var values = arguments;

Return format. replace (
FB. String. format. _ formatRE,
Function (str, m ){
Var
Index = parseInt (m. substr (1), 10 ),
Value = values [index + 1];
If (value = null | value = undefined ){
Return '';
}
Return value. toString ();
}
);
}

Usage:

The Code is as follows:

Format ('{0} .facebook.com/?1=', 'www', 'login. php ');
//-> Www.facebook.com/login.php

Exchange the values of two variables

The Code is as follows:

Var foo = 1;
Var bar = 2;
Foo = [bar, bar = foo] [0];

RegExp Looping

The Code is as follows:

String. prototype. format = function (/* args */){
Var args = arguments;
Return this. replace (
/\ {(\ D +) \}/g,
Function (full, idx ){
Return args [idx];
})
}

'Hello {0}, How {1} '. format ('bob', 'you domain ');
// => Hello Bob, How you doinhttp: // mazesoul.github.com/readability_idioms_and_compression_tolerance/42431.0

Define is to run the Function

The Code is as follows:

(Function (){
// Do something
})();

This is indeed the simplest technique, but also the most practical one. It lays the foundation for JavaScript encapsulation.

Ternary Computation

The Code is as follows:

Var some = con1? Val1:
Con2? Val2:
Con3? Val3:
DefaultVal;

Function registration-call Mechanism

From CKEditor, I did the extraction.

The Code is as follows:

(Function (){
Var fns = [];
// Convert objects with accessible subscript attributes into Arrays
// Note that DOMNodeList in IE will fail
Function toArray (arrayLike, index ){
Return Array. prototype. slice. call (arrayLike, index | 0 );
}
Window. Util = {
'Addfunction': function (fn, scope ){
Return fns. push (function (){
Return fn. apply (scope | window, arguments );
})-1;
},

'Removefunction': function (index ){
Fns [index] = null;
},

'Callfunction': function (index ){
Var fn = fns [index];

Return fn & fn. apply (window, toArray (arguments, 1 ));
}
};
})();
// Application Scenario
Var fnId;
// Add a global function to the closure.
(Function (){
FnId = Util. addFunction (function (msg ){
Alert (msg );
});
})();

// Call
Util. callFunction (fnId, 'Hello, World'); //-> 'hello, world ';

Short circuit operation

The Code is as follows:

Var something = 'xxxx ';
Console. log (true & something); //-> 'xxx ';
Console. log (false & something); //-> false
Console. log (true | something); //-> true
Console. log (false | something); //-> something