Position descriptors represent an X or Y coordinate. The top-left corner of the page is (0, 0) and the values increase downward and to the right.
Stability: 2 - Unstable
Position descriptors may be compared to another position descriptor or to a number.
At present, comparisons are artificially limited. Comparing an X-coordinate to a Y-coordinate will result in an exception. This is an experiment to see if it's more useful to fail fast than to provide flexibility. Please share your opinion about this tradeoff by contributing to issue #6.
Position descriptors implement the following methods. They're useful when you want to compare positions that aren't exactly aligned.
Stability: 2 - Unstable
Create a new descriptor that is further down the page or to the right.
descriptor.plus(amount)
amount (SizeDescriptor or number)The number of pixels to move the descriptor.
Example: "The top of the sidebar is 10px below the bottom of the navigation bar."
sidebar.assert({
top: navbar.bottom.plus(10)
});Stability: 2 - Unstable
Create a new descriptor that is further up the page or to the left.
descriptor.minus(amount)
amount (SizeDescriptor or number)The number of pixels to move the descriptor.
Example: "The logo is 15px inside the navigation bar."
logo.assert({
right: navbar.right.minus(15)
});