jquery-ui.js:8056 Uncaught TypeError: Cannot read property ‘left’ of undefined

I have no clue why my sign up page have these errors jquery-ui.js:8056 Uncaught TypeError: Cannot read property ‘left’ of undefined Some codes

Sortable jquery rectangle in grid (relative dimensions)

Hello I have a rectangle that I want to move inside a grid. The rectangle is a multiple of the grid cells. So width=100% and height=100% is 1 cell, while width=200% and height=200% is 4 cells. Now I …