What conditions does a function have to meet for the following to be true?
$$\displaystyle\lim_{x\to 0}\frac{\partial}{\partial x}f(x,y)=\frac{\partial}{\partial x}\lim_{x\to 0}f(x,y)$$
I've looked both on MSE and tried googling this question as well but I can't find a good answer. Any explanation or resources you could point me to would be greatly appreciated!