TypeError: ctx.ellipse is not a function

[vikasacharya16]

this is working

ctx.fillRect(x - 50, y - 50, 100, 100);  
ctx.arc(x, y, 50, 0, Math.PI + (Math.PI * 2) / 2, 3 % 2 == 1);

this is not working

ctx.ellipse(x, y, 50, 50, Math.PI / 4, 0,  2 * Math.PI);

giving an error

TypeError: ctx.ellipse is not a function. (In 'ctx.ellipse(x, y, 50, 50, Math.PI / 4, 0, 2 * Math.PI)', 'ctx.ellipse' is undefined)

I'm working on Adroid.