How do I insert dynamic text inside rectangle in jsPDF?

Question

I want to add some text inside my jsPDF rectangle.

doc.rect(x, y, w, h, style)
doc.text(x+10,y+20,"Hello");
// the more doc.text() I add, the height of the rectangle should keep on increasing

I want my text to always remain inside the rectangle, no matter how much I add. How do I do that?