Question

这是我的代码：

function active_area(width, t_width, height) {
    this.width = width;
    this.height = height;
    this.t_width = t_width; //width of toolbar

    this.dotes  = 20;
    this.gridStep = this.width/this.dotes;

    this.active_layer = -1;
    this.layers_array = [];

}
    active_area.prototype.init = function () {
        this.canvas = createCanvas(this.width+this.t_width, this.height);
        this.canvas.parent('mapper');

        this.addButton(10, 10, 'Zoom out', this.zoomOut);
        this.addButton(10, 50, 'Zoom in', this.zoomIn);
        this.addButton(30, 30, 'Add layer', this.addLayer);

        this.drawGrid();
    };

    active_area.prototype.addButton = function(x, y, name, func){
        var pos_x = this.width+x;
        var add_layer = createDiv();
        add_layer.position(pos_x, height + y);
        add_layer.html('<paper-button>'+name+'</paper-button>');
        add_layer.mouseClicked(func);
    };

    active_area.prototype.zoomOut = function () {
        console.log('zoom out');
        console.log('dotes:'+this.dotes);
        this.dotes = this.dotes*2;
        console.log('dotes:'+this.dotes);
        redraw();
        //this.drawGrid();
    };

方法问题zoomOut：我无法从类active_area访问this.dotes，drawGrid无法访问。这个方法调用精细，监听器工作，但如何访问类范围？

Answer 1

你需要绑定它

this.addButton(10, 10, 'Zoom out', this.zoomOut.bind(this));
this.addButton(10, 50, 'Zoom in', this.zoomIn.bind(this));
this.addButton(30, 30, 'Add layer', this.addLayer.bind(this));

Javascript：将对象的方法作为指针传递

1 个答案: