Wait until an element stops changing

Samples the prop property of every element matching target (or the current context) until the sampled value has held still for for_ms milliseconds: text has stopped arriving, or an animation has come to rest. prop = "rect" samples the bounding box instead of a property, rounded to whole pixels.

Usage

pz_wait_for_stable(
  ctx,
  ...,
  target = NULL,
  prop = "textContent",
  for_ms = 500,
  timeout = NULL
)

Arguments

ctx

A paparazzi context.

...

Checked empty; reserved for future use.

target

A CSS selector string, a pz_loc() spec, or a list of specs and strings (a union matching any of them). NULL means the current context: the pinned set at a scoped context, the page body at the root.

prop

The element property to sample: any single JavaScript property name ("textContent", "value", "scrollTop", ...), or "rect" for the bounding box.

for_ms

Milliseconds the sampled value must hold still before the wait passes.

timeout

Seconds before giving up; NULL uses the session default.

Value

ctx, invisibly.

Details

The wait first waits (up to timeout) for target to match, then samples within a second, separate timeout budget of its own: a target that appears near the locator deadline still gets its full for_ms window.

There is deliberately no element-state wait: pz_expect_visible(), pz_expect_hidden(), and pz_expect_exists() with not = TRUE already retry, so they wait.

See also

pz_wait_for_js(), pz_wait_for_navigation()

Examples

page <- pz_open(pz_example("tasks"))

# The status line reads "Saving..." and then "Saved"; wait for it to settle
page |>
  pz_act_type("Buy milk", target = "#task-title") |>
  pz_act_click("#add-task") |>
  pz_wait_for_stable(target = "#status", for_ms = 500)
pz_get_text(page, target = "#status")
#> [1] "Saved “Buy milk”."
pz_close(page)