How to determine exactly and quickly the total memory used by a web page?

Not the heap size, but the total memory used by a single web page.

To demonstrate how to accurately and quickly measure the total memory used by a web page, I will use a script first gradually filling the memory and then gradually releasing it.

let a, b, c;
printMemory('baseline')
    .then(() => {
        a = makeString(10);
        return printMemory('a = makeString(10)');
    })
    .then(() => {
        b =…