# What is the mechanism of errors highlighting by WProofreader and SCAYT plugin for CKEditor 4?

A request in SCAYT or WProofreader is a set of sentences totaling up to 4 sentences. Under a “sentence” (or a token) we understand a string of text which ends with one of the punctuation symbols such as (.!?\n) followed by a space and the word that starts with capital letter by or the end of the paragraph (e.g. \</p>).

The requests to our AppServer will be sent immediately after pressing **Enter** or **Space** keys or in 2 seconds for SCAYT or 500 ms for WProofreader after stop the typing. If there are completed sentences in the received response, all the found errors will be highlighted. Otherwise, new requests containing only sentences where changes were made will be sent. Such behavior is present due to the fact that the sentence was not completed by the time a response arrives, it might have been changed, thus, a new request will be sent.

Right now the mechanism of errors highlighting in the plugin itself is the same. The only difference that now the minimal unit is a sentence but not a single word. Yes, it might have a slight delay and cause some inconvenience to an end-user. But this is done intentionally to avoid additional CPU load. Yes, we can make certain optimizations and tricks to smooth the visual delay for the end users but it would take the additional time. We are going to try them but for WProofreader only, and this feature is already in our backlog.


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