jQuery挖源码——事件绑定

jQuery版本：2.1.4

• 最常用事件绑定bind，调用了on。

bind: function( types, data, fn ) {
        return this.on( types, null, data, fn );
    }

        对应解绑unband，调用了off。

unbind: function( types, fn ) {
        return this.off( types, null, fn );
    }

• 只执行一次的one绑定，赤裸裸调用on。

one: function( types, selector, data, fn ) {
        return this.on( types, selector, data, fn, 1 );
    }

• 委托delegate，调用on

delegate: function( selector, types, data, fn ) {
        return this.on( types, selector, data, fn );
    }

        undelegate调用off

undelegate: function( selector, types, fn ) {
        // ( namespace ) or ( selector, types [, fn] )
        return arguments.length === 1 ? this.off( selector, "**" ) : this.off( types, selector || "**", fn );
    }

• 最后揭开on的面纱。

参数：

• types 事件类型
• selector 委托中是子元素。（曾经的one中貌似没有这个参数）
• data 参数
• fn  事件处理函数
• one  是否one绑定

on: function( types, selector, data, fn, /*INTERNAL*/ one ) {
        var origFn, type;

        // Types can be a map of types/handlers
        if ( typeof types === "object" ) {
            // ( types-Object, selector, data )
            if ( typeof selector !== "string" ) {
                // ( types-Object, data )
                data = data || selector;
                selector = undefined;
            }
            for ( type in types ) {
                this.on( type, selector, data, types[ type ], one );
            }
            return this;
        }

        if ( data == null && fn == null ) {
            // ( types, fn )
            fn = selector;
            data = selector = undefined;
        } else if ( fn == null ) {
            if ( typeof selector === "string" ) {
                // ( types, selector, fn )
                fn = data;
                data = undefined;
            } else {
                // ( types, data, fn )
                fn = data;
                data = selector;
                selector = undefined;
            }
        }
        if ( fn === false ) {
            fn = returnFalse;
        } else if ( !fn ) {
            return this;
        }

        if ( one === 1 ) {
            origFn = fn;
            fn = function( event ) {
                // Can use an empty set, since event contains the info
                jQuery().off( event );
                return origFn.apply( this, arguments );
            };
            // Use same guid so caller can remove using origFn
            fn.guid = origFn.guid || ( origFn.guid = jQuery.guid++ );
        }
        return this.each( function() {
            jQuery.event.add( this, types, fn, data, selector );
        });
    }

对应解绑off

off: function( types, selector, fn ) {
        var handleObj, type;
        if ( types && types.preventDefault && types.handleObj ) {
            // ( event )  dispatched jQuery.Event
            handleObj = types.handleObj;
            jQuery( types.delegateTarget ).off(
                handleObj.namespace ? handleObj.origType + "." + handleObj.namespace : handleObj.origType,
                handleObj.selector,
                handleObj.handler
            );
            return this;
        }
        if ( typeof types === "object" ) {
            // ( types-object [, selector] )
            for ( type in types ) {
                this.off( type, selector, types[ type ] );
            }
            return this;
        }
        if ( selector === false || typeof selector === "function" ) {
            // ( types [, fn] )
            fn = selector;
            selector = undefined;
        }
        if ( fn === false ) {
            fn = returnFalse;
        }
        return this.each(function() {
            jQuery.event.remove( this, types, fn, selector );
        });
    },