Which javascript methods can be used to serialize an object into a string and deserialize a JSON string into an object, respectively?

myArraym can have one level, two levels, or more levels.
Which statement flattens myArray when it can be arbitrarily nested?

Refer to HTML below:
<p> The current status of an Order: <span id ="status"> In Progress </span> </p>.
Which JavaScript statement changes the text 'In Progress' to 'Completed' ?

Refer to the code:

Given the code above, which three properties are set for pet1? Choose 3 answers

Universal Containers (UC) just launched a new landing page, but users complain that the website is slow. A developer found some functions any that might cause this problem. To verify this, the developer decides to execute everything and log the time each of these three suspicious functions consumes.
Which function can the developer use to obtain the time spent by every one of the three functions?