JavaScript's pretty code snippets _javascript tips

Dynamic construction of regular expressions

Copy Code code as follows:

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

From sizzle, when dynamically building regular, this avoids character escaping.

More flexible and ingenious Digital 0

Copy Code code as follows:

function Prefixinteger (num, length) {
Return (Num/math.pow (length)). toFixed (length). substr (2);
}

Take the maximum and minimum values of an array

Copy Code code as follows:

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

To produce pretty random strings

Copy Code code as follows:

Math.random (). toString. substring (2); 8-bit
Math.random (). toString. substring (2); 16-bit

Get time stamp

Relative to
var timeStamp = (new Date). GetTime ();
The following ways are more convenient:

Copy Code code as follows:

var timeStamp = number (new Date);

Convert to numeric value and rounding

Copy Code code as follows:

var result = ' 3.1415926 ' | 0; 3

String formatting

Copy Code code 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 ();
}
);
}

Use:

Copy Code code as follows:

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

Swap the value of a two variable

Copy Code code as follows:

var foo = 1;
var bar = 2;
foo = [bar, bar=foo][0];

REGEXP Looping

Copy Code code 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 Doin ');
=> Hello Bob, how do you doinhttp://mazesoul.github.com/readability_idioms_and_compression_tolerance/#31.0

Definition is run function

Copy Code code as follows:

(function () {
Do something
} )();

This is really the simplest technique, but it is also the most practical technique. Lays the foundation for JavaScript encapsulation.

Ternary operation

Copy Code code as follows:

var some = Con1? Val1:
Con2? Val2:
Con3? VAL3:
Defaultval;

A function registration-invocation mechanism

From CKEditor, I made the extraction.

Copy Code code as follows:

(function () {
var FNS = [];
Converts an object with the available subscript access attribute to an array
Note that IE Domnodelist 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 Scenarios
var Fnid;
In the closure, add a function that can be called globally
(function () {
Fnid = util.addfunction (function (msg) {
Alert (msg);
} );
} )();

Call
Util.callfunction (Fnid, ' Hello, World '); -> ' Hello,world ';

Short circuit operation

Copy Code code 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