Find elapsed time in javascript

Question

I\'m new to JavaScript and I\'m trying to write a code which calculates the time elapsed from the time a user logged in to the current time.

Here is my code:-

Answer 1

What I found useful is a 'port' of a C++ construct (albeit often in C++ I left show implicitly called by destructor):

var trace = console.log
function elapsed(op) {
    this.op = op
    this.t0 = Date.now()
}
elapsed.prototype.show = function() {
    trace.apply(null, [this.op, 'msec', Date.now() - this.t0, ':'].concat(Array.from(arguments)))
}

to be used - for instance:

function debug_counters() {
    const e = new elapsed('debug_counters')
    const to_show = visibleProducts().length
    e.show('to_show', to_show)
}