将variables值replace为另一个值

yMax = 100; this.dataBoundaries = { x: function () { var lastCol = that.extractLastColumn(); return [d3.min(lastCol), d3.max(lastCol)]; }, y: [ 0, 100 ] }; console.log(this.dataBoundaries); 

上面的代码将导致打印y与另一个值而不是[0,100] => [0,34 …..]，为什么会发生这种情况？