When does the eventloop in the js start the first tick, and when does the tick, end? what process does the tick usually go through?

1. Many articles have talked about how eventloop runs, how to read task queues, macro tasks, micro tasks, and so on, but I don"t quite understand when the first tick? started

.
Macro tasks: script overall code, setTimeout, etc.
Micro tasks: promise, etc.
< H2 > when does it start? < / H2 >

statement 1: even if you start a tick when executing global script code

statement 2: when you start reading asynchronous tasks from the task queue after all the Synchronize code is executed, you start tick, for the first time. This asynchronous task may be micro-tasks such as promise

. < H2 > when does it end? < / H2 >

statement 1: if there is a micro task, then every time the micro task is executed, the tick ends, that is, the macro task-micro task. If there is no micro task in the tick, the execution of the macro task is over.

< H2 > all the above statements are that my own guesses may not be accurate. I hope the boss will answer the questions. < / H2 >
Javascript
Mar.28,2021
< H2 > recent search data and come to the conclusion: < / H2 >

the first Tick starts with the execution of global script code.
the end is the end of UI render, and the current round of tick is over.
if there is a micro task, it will execute all the micro tasks before executing UI render, and then end

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