QUnitソース読解(1):ツール関数

QUnitはJavaScriptユニットテストフレームワークです.もっと具体的にrefを紹介します.  http://qunitjs.com/
次はQUnitのコードです.

(function() {

    function F() {}

    F.prototype = QUnit;

    QUnit = new F();

    // Make F QUnit's constructor so that we can add to the prototype later

    QUnit.constructor = F;

}());

What does it mean? Idon't know.コードcopyをブラウザに直接テストし、定義します.

QUnit = {

            add:function(a, b){return a+b;},

            id: 1

        };

デバッグ後の検出:

 

    id    
function id( name ) {

    return !!( typeof document !== "undefined" && document && document.getElementById ) &&

        document.getElementById( name );

}

!!感嘆符の役割は何ですか??C/C++の連続2回とは明らかに違います!の
彼は三元演算子に相当し、boolean値を返します.

var ret = !!document.getElementById

Equals to the following:

var ret = document.getElementById ? true : false;

Other practical techniques:

var num = 100;

num = num +""; //var1+""    string

document.write(typeof num+" : "+num+"<br/>");

            

num = ~~num; //~~var1    int

document.write(typeof num+" : "+num+"<br/>");

            

num = [num]//[var1]    array

document.write(typeof num+" : "+"num instanceof Array"+(num instanceof Array)+" "+num+"<br/>");

//   elem     type   ，      fn

//  Firefox，chrome IE  

function addEvent( elem, type, fn ) {

    if ( elem.addEventListener ) {

        elem.addEventListener( type, fn, false );

    } else if ( elem.attachEvent ) {

        elem.attachEvent( "on" + type, fn );

    } else {

        fn();

    }

}

//   b            a 

function extend( a, b ) {

    for ( var prop in b ) {

        if ( b[ prop ] === undefined ) {

            delete a[ prop ];



        // Avoid "Member not found" error in IE8 caused by setting window.constructor

        } else if ( prop !== "constructor" || a !== window ) {

            a[ prop ] = b[ prop ];

        }

    }



    return a;

}

//             
// so far supports only Firefox, Chrome and Opera (buggy), Safari (for real exceptions)

// Later Safari and IE10 are supposed to support error.stack as well

// See also https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Error/Stack

function extractStacktrace( e, offset ) {

    offset = offset === undefined ? 3 : offset;



    var stack, include, i, regex;



    if ( e.stacktrace ) {

        // Opera

        return e.stacktrace.split( "
" )[ offset + 3 ];

    } else if ( e.stack ) {

        // Firefox, Chrome

        stack = e.stack.split( "
" );

        if (/^error$/i.test( stack[0] ) ) {

            stack.shift();

        }

        if ( fileName ) {

            include = [];

            for ( i = offset; i < stack.length; i++ ) {

                if ( stack[ i ].indexOf( fileName ) != -1 ) {

                    break;

                }

                include.push( stack[ i ] );

            }

            if ( include.length ) {

                return include.join( "
" );

            }

        }

        return stack[ offset ];

    } else if ( e.sourceURL ) {

        // Safari, PhantomJS

        // hopefully one day Safari provides actual stacktraces

        // exclude useless self-reference for generated Error objects

        if ( /qunit.js$/.test( e.sourceURL ) ) {

            return;

        }

        // for actual exceptions, this is useful

        return e.sourceURL + ":" + e.line;

    }

}



function sourceFromStacktrace( offset ) {

    try {

        throw new Error();

    } catch ( e ) {

        return extractStacktrace( e, offset );

    }

}

         
 // Safe object type checking

    is: function( type, obj ) {

        return QUnit.objectType( obj ) == type;

    },



    objectType: function( obj ) {

        if ( typeof obj === "undefined" ) {

                return "undefined";

        // consider: typeof null === object

        }

        if ( obj === null ) {

                return "null";

        }



        var type = toString.call( obj ).match(/^\[object\s(.*)\]$/)[1] || "";



        switch ( type ) {

            case "Number":

                if ( isNaN(obj) ) {

                    return "nan";

                }

                return "number";

            case "String":

            case "Boolean":

            case "Array":

            case "Date":

            case "RegExp":

            case "Function":

                return type.toLowerCase();

        }

        if ( typeof obj === "object" ) {

            return "object";

        }

        return undefined;

    },

           
// Trigger an event on an element.

    // @example triggerEvent( document.body, "click" );

    triggerEvent: function( elem, type, event ) {

        if ( document.createEvent ) {

            event = document.createEvent( "MouseEvents" );

            event.initMouseEvent(type, true, true, elem.ownerDocument.defaultView,

                0, 0, 0, 0, 0, false, false, false, false, 0, null);



            elem.dispatchEvent( event );

        } else if ( elem.fireEvent ) {

            elem.fireEvent( "on" + type );

        }

    },

              
function inArray( elem, array ) {

    if ( array.indexOf ) {

        return array.indexOf( elem );

    }



    for ( var i = 0, length = array.length; i < length; i++ ) {

        if ( array[ i ] === elem ) {

            return i;

        }

    }



    return -1;

}

            
function getText( elems ) {

    var i, elem,

        ret = "";



    for ( i = 0; elems[i]; i++ ) {

        elem = elems[i];



        // Get the text from text nodes and CDATA nodes

        if ( elem.nodeType === 3 || elem.nodeType === 4 ) {

            ret += elem.nodeValue;



        // Traverse everything else, except comment nodes

        } else if ( elem.nodeType !== 8 ) {

            ret += getText( elem.childNodes );

        }

    }



    return ret;

}