Question

我已经看到这个解决方案在构造函数中定义事件时有效：

Accessing class member variables inside an event handler in Javascript

但是当在原型中定义处理程序时，它没有从前一个解决方案中看到“var _self”的范围。是否有适用于类似下面代码的变体？

问题在于“幻灯片”处理程序中的“this”...引用HTML元素而不是MyView中的成员变量。

function MyView(wrapperDiv)
{
    this.contentW = 1200;
    this.vboxW = 600;
    this.vboxH = 400;
    this.vboxX = 0;
    this.vboxY = 0;
}

MyView.prototype = {

    initHorizontalScrollBar : function ($bar)
    {
        //create the wrappers for the slider
        if($bar.find('.slider-wrap').length==0)
            $bar.append('<\div class="slider-wrap"><\div class="slider-horizontal"><\/div><\/div>');//append the necessary divs so they're only there if needed
        $bar.find('.slider-wrap').width(this.svgWidth);

        //initialize the JQueryUI slider
        $bar.find('.slider-horizontal').slider({
            orientation: 'horizontal',
            min: 0,
            max: 100,
            range:'min',
            value: 0,
            slide: function(event, ui) {

                var difference = this.contentW-this.vboxW;
                if(difference<=0)
                    return;
                this.vboxX =  (ui.value) / 100 * ( this.contentW-this.vboxW);       // 0 >= ui.value <= 100
                this.svg.setAttribute("viewBox", toViewBoxString(this.vboxX, this.vboxY, this.vboxW, this.vboxH));
                $('ui-slider-range').width(ui.value+'%');//set the height of the range element
            }
          });     


        this.sizeHScrollbar();
    }
};

Answer 1

您只需要在initHorizontalScrollBar方法中添加一个包含正确引用的变量：

MyView.prototype = {

    initHorizontalScrollBar : function ($bar)
    {
        var _self = this;
        //create the wrappers for the slider
        if($bar.find('.slider-wrap').length==0)
            $bar.append('<\div class="slider-wrap"><\div class="slider-horizontal"><\/div><\/div>');//append the necessary divs so they're only there if needed
        $bar.find('.slider-wrap').width(this.svgWidth);

        //initialize the JQueryUI slider
        $bar.find('.slider-horizontal').slider({
            orientation: 'horizontal',
            min: 0,
            max: 100,
            range:'min',
            value: 0,
            slide: function(event, ui) {

                var difference = _self.contentW - _self.vboxW;
                if(difference<=0)
                    return;
                _self.vboxX =  (ui.value) / 100 * ( _self.contentW - _self.vboxW);       // 0 >= ui.value <= 100
                this.svg.setAttribute("viewBox", toViewBoxString(_self.vboxX, _self.vboxY, _self.vboxW, _self.vboxH));
                $('ui-slider-range').width(ui.value+'%');//set the height of the range element
            }
          });     


        this.sizeHScrollbar();
    }
};

如何在类原型中定义的事件处理程序中访问类成员变量 - Javascript

1 个答案: