Beautiful code snippets for JavaScript_javascript tips

Dynamically construct regular expressions

Copy code The code is as follows:

new RegExp( Expr.match[ type ].source ( /(?![^[]*])(?![^(]*))/.source) )

from sizzle, when dynamically building regular expressions, this avoids character escaping .

More flexible and clever number zero padding

Copy code The code is as follows:

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

Get the maximum and minimum value of the array

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

Generate beautiful random strings

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

Get timestamp

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

Copy code The code is as follows:

var timeStamp = Number(new Date);

Convert to numeric value and round

Copy code The code is as follows:

var result = '3.1415926' | 0; // 3

String formatting

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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]; ;
}
);
}


Use:

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The code is as follows: format('{0}.facebook.com/{1}', 'www', 'login.php'); //-> www. facebook.com/login.php

Exchange the values ​​of two variables

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The code is as follows:var foo = 1;var bar = 2 ;

foo = [bar, bar=foo][0];

RegExp Looping

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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 doin');
// => Hello Bob, How you doinhttp://mazesoul.github.com/ Readability_idioms_and_compression_tolerance/#31.0

Define and run functions

Copy code The code is as follows:

( function() {
// do something
} )();

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

Ternary operation

Copy code The code is as follows:

var some = con1 ? val1 :
con2 ? val2 :
con3 ? val3 :
defaultVal;

A function registration-calling mechanism

From CKEditor, I did the extraction.

Copy code The code is as follows:

( function() {
var fns = [ ];
// Convert objects whose attributes can be accessed by subscripts into arrays
// Note that DOMNodeList will fail under IE
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;
// 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 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