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CHAPTER 13
Dipping Our Toes, Very Tentatively,
into JavaScript
If the Good Lord had wanted us to enjoy ourselves, he wouldn’t have granted us his precious
gift of relentless misery.
— John Calvin (as portrayed in
Calvin and the Chipmunks )Our new validation logic is good, but wouldn’t it be nice if the error messages disap‐
peared once the user started fixing the problem? For that we’d need a teeny-tiny bit of
JavaScript.
We are utterly spoiled by programming every day in such a joyful language as Python.
JavaScript is our punishment. So let’s dip our toes in, very gingerly.
I’m going to assume you know the basics of JavaScript syntax. If you
haven’t read
JavaScript: The Good Parts ,go and get yourself a copy
right away! It’s not a very long book.
Starting with an FT
Let’s add a new functional test to the
ItemValidationTest
class:
functional_tests/test_list_item_validation.py (ch14l001).
def
test_error_messages_are_cleared_on_input
(
self
):
# Edith starts a new list in a way that causes a validation error:
self
.
browser
.
get
(
self
.
server_url
)
self
.
get_item_input_box
()
.
send_keys
(
'
\n
'
)
error
=
self
.
browser
.
find_element_by_css_selector
(
'.has-error'
)
self
.
assertTrue
(
error
.
is_displayed
())
#
# She starts typing in the input box to clear the error
self
.
get_item_input_box
()
.
send_keys
(
'a'
)
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