Here we add the counter property to track the total calls count:… A property assigned to a function like sayHi.counter = 0 does not define a local variable counter… In other words, a property counter and a variable let counter are two unrelated things.… For instance, we can rewrite the counter function example from the chapter Variable scope, closure to… Rest parameters are not counted.
When the operator goes after the variable, it is in “postfix form”: counter++.… The “prefix form” is when the operator goes before the variable: ++counter.… Both of these statements do the same thing: increase counter by 1.
Is there any difference?… increments counter and returns the new value, 2.… ++ also increments counter but returns the old value (prior to increment).
Below, makeCounter creates the “counter” function that returns the next number on each invocation:… If we create multiple counters, will they be independent? What’s going on with the variables here?… Environment reference is taken from counter.… [[Environment]]:
Now when the code inside counter() looks for count… Here’s the state after the execution:
If we call counter() multiple
A single run of count does a part of the job (*), and then re-schedules itself (**) if needed:
First… run counts: i=1...1000000.… Second run counts: i=1000001..2000000.
…and so on.… There’s not much difference in the overall counting time.… () and see that we’ll need to count() more, we schedule that immediately, before doing the job.
by the key.
map.clear() – removes everything from the map.
map.size – returns the current element count… The same does not count for Object.… the set, otherwise false.
set.clear() – removes everything from the set.
set.size – is the elements count… A visitor must be “counted” only once.… the set, otherwise false.
set.clear() – removes everything from the set.
set.size – is the elements count
So, technically, the current element count of a WeakMap is not known.… For instance, we have code that keeps a visit count for users.… The information is stored in a map: a user object is the key and the visit count is the value.… When a user leaves (its object gets garbage collected), we don’t want to store their visit count anymore… Here’s an example of a counting function with Map:
response.json() and other methods, response.body gives full control over the reading process, and we can count… To log the progress, we just need for every received fragment value to add its length to the counter.
A real ninja will never use i as the counter in a "for" loop. Anywhere, but not here.… An exotic variable as a loop counter is especially cool if the loop body takes 1-2 pages (make it longer… deep inside the loop, they won’t be able to quickly figure out that the variable named x is the loop counter
Behavior: Counter.For instance, here the attribute data-counter adds a behavior: “increase value on click… There can be as many attributes with data-counter as we want.
Async scripts are great when we integrate an independent third-party script into the page: counters,… And async is used for independent scripts, like counters or ads.
When we run it, there are two if execution branches:
If passed args count… implementations usually both keep the function callable normally and return the partial if the arguments count
If the code has anything subtle and counter-intuitive, it’s definitely worth commenting.
As there’s no match, the greedy quantifier + decreases the count… The order of combinations will change, but not their total count.… There’s no need to lower the repetitions count in \w+ or to split it into two words \w+\w+ and so on.… We covered two ways how to solve it:
Rewrite the regexp to lower the possible combinations count.
JavaScript, we can shorten a number by appending the letter "e" to it and specifying the zeroes count… In other words, e multiplies the number by 1 with the given zeroes count… we could write the same as:
If we count… But what if we apply a discount of 30%? In practice, totally evading fractions is rarely possible.… Summary.To write numbers with many zeroes:
Append "e" with the zeroes count to the number.
The month count starts with 0 (Jan), up to 11 (Dec).… Months are counted from zero (yes, January is a zero month).… Days of week in getDay() are also counted from zero (that’s Sunday).
range:
store.get(query) – search for the first value by a key or a range.
store.getAll([query], [count… ]) – search for all values, limit by count if given.
store.getKey(query) – search for the first key that… satisfies the query, usually a range.
store.getAllKeys([query], [count]) – search for all keys that… satisfy the query, usually a range, up to count if given.
store.count([query]) – get the total count… ) – advance the cursor count times, skipping values.
continue([key]) – advance the cursor to the next
When the document scrolled:
pageY – document-relative coordinate stayed the same, it’s counted… All window coordinates are counted from the top-left corner, including these ones.
If pos is negative, then it’s counted from the end of the string.… They mean the position is counted from the string end:… The first argument may be negative, to count
In short, document-relative coordinates pageX/Y are counted from the left-upper corner of the document… , and do not change when the page is scrolled, while clientX/Y are counted from the current window left-upper
It has a few advanced forms, let’s see examples:
The exact count: {5}
\d{5} denotes exactly 5 digits
Inline variable declaration
Here, the “counter
We forever deny access to information about right-clicks for any outer code, including counters that
Here are the Unicode values of some characters:
Character
Unicode
Bytes count in Unicode
a
0x0061
sandbox.Usually, beforeEach/afterEach and before/after are used to perform initialization, zero out counters
That’s good for functionality that doesn’t depend on anything, like counters, ads, document-level event
But of course in the result only the first two will be counted, so the result in the code above is 3.
new one to the array:
The total count… To be precise, it is actually not the count of values in the array, but the greatest numeric index plus
For simple patterns it’s doable, but for more complex ones counting parentheses is inconvenient.
For instance, when we need a list of users, a request returns a pre-defined count (e.g. 100 users) –
there are two important differences:
Transitions inside the element, to/from descendants, are not counted
For historical reasons, returning a non-empty string also counts
E.g. a decorator may count how many times a function was invoked and how much time it took, and expose
Keyboard events should be used when we want to handle keyboard actions (virtual keyboard also counts)
The engine keep backtracking: it decreases the count of repetition for '.' until the rest of the pattern
ends,
isCollapsed – true if selection selects nothing (empty range), or doesn’t exist.
rangeCount – count