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There are three variants of type conversion, that happen in various situations.… The multiplication obj * 2… first converts the object to primitive (that’s a string "2").… Then "2" * 2 becomes 2 * 2 (the string is converted to number).

For example, here 1+2 results in 3, while the function call hello("debugger") returns nothing… That’s useful when we have many breakpoints in various files.… Oh, and also you can click at various places of dev tools and just see what’s showing up.

In this article we’ll cover various methods that work with regexps in-depth. str.match(regexp).The method… part of the string before the match $' inserts a part of the string after the match $n if n is a 1-2… parentheses, so the replacement function is called with 5 arguments: the first is the full match, then 2

The parent constructor also sets the name property to "Error", so in the line (2) we reset… widespread technique: a function handles low-level exceptions and creates higher-level errors instead of various

Wrote some code, testing: f(1) works, but f(2) doesn’t work. We fix the code and now f(2) works.… They run our functions in various ways and compare results with the expected.… Here it checks that the result of pow(2, 3) equals 8.

As of now, Pointer Events Level 2 specification is supported in all major browsers, while the newer Pointer… Events Level 3 is in the works and is mostly compatible with Pointer Events level 2.… We can use this property to react differently on various pointer types.

Let’s cover various events that accompany data updates.… A user may switch between various applications, copy/paste different things, and a browser page shouldn

For example, to calculate pow(2, 4) the recursive variant does these steps: pow(2, 4) = 2 * pow(2, 3… ) pow(2, 3) = 2 * pow(2, 2) pow(2, 2) = 2 * pow(2, 1) pow(2, 1) = 2 So, the recursion reduces a function… Here’s the context stack when we entered the subcall pow(2, 2): Context: { x: 2, n: 2, at line… n: 1, at line 1 } pow(2, 1) Context: { x: 2, n: 2, at line 5 } pow(2, 2)… pow(2, 2) Context: { x: 2, n: 3, at line 5 } pow(2, 3) The execution of pow(2, 2) is

There are various ways to solve this problem such as func.bind().

Otherwise, if the first digit is 2, then the next must be [0-3].… (no other first digit is allowed) We can write both variants in a regexp using alternation: [01]\d|2[… If we glue hours and minutes together, we get the pattern: [01]\d|2[0-3]:[0-5]\d.… The alternation | now happens to be between [01]\d and 2[0-3]:[0-5]\d.… Let’s correct that by enclosing “hours” into parentheses: ([01]\d|2[0-3]):[0-5]\d.

There may be 2, 3, 4 or more.… In the demo above they are labeled: 1, 2, 3. Build segments between control points 1 → 2 → 3.… 2 → 3, 3 → 4.… There will be N-2 segments. Repeat step 2 until there is only one point.… 0 + 2(1−t)t * 0.5 + t2 * 1 = (1-t)t + t2 = t y = (1−t)2 * 0 + 2(1−t)t * 1 + t2 * 0 = 2(1-t)t = –2t2 +

Good resources that show the current state of support for various features: https://compat-table.github.io

operand is 2.… The 2 gets concatenated to '1', so it’s like '1' + 2 = "12" and "12" + 2 = "… For example, write (1 + 2) * 2. There are many operators in JavaScript.… So, the alert shows 2.… It’s like (a = 1 + 2), 3 + 4.

architecture Provide a high-level overview of components, how they interact, what’s the control flow in various

Surrogate pairs.All frequently used characters have 2-byte codes (4 hex digits).… Initially, JavaScript was based on UTF-16 encoding that only allowed 2 bytes per character.… But 2 bytes only allow 65536 combinations and that’s not enough for every possible symbol of Unicode.… So rare symbols that require more than 2 bytes are encoded with a pair of 2-byte characters called “a… As a side effect, the length of such symbols is 2:

Most characters are encoded with 2 bytes, but that allows to represent at most 65536 characters.… are the Unicode values of some characters: Character Unicode Bytes count in Unicode a 0x0061 2… ≈ 0x2248 2 𝒳 0x1d4b3 4 𝒴 0x1d4b4 4 😄 0x1f604 4 So characters like a and ≈ occupy 2 bytes… The point is that length treats 4 bytes as two 2-byte characters.… By default, regular expressions also treat 4-byte “long characters” as a pair of 2-byte ones.

In contrast, objects are used to store keyed collections of various data and more complex entities.… And they extend it in various ways. Objects in JavaScript are very powerful.

HTML specification Describes the HTML language (e.g. tags) and also the BOM (browser object model) – various

second (*), Then the .then handler is called (**), which in turn creates a new promise (resolved with 2… As the result is passed along the chain of handlers, we can see a sequence of alert calls: 1 → 2 → 4.… That handler is in the line (**), it shows 2 and does the same thing.… So the output is the same as in the previous example: 1 → 2 → 4, but now with 1 second delay between… In the example above resolve(2) is called after 1 second (**).

base=2 is mostly for debugging bitwise operations, digits can be 0 or 1.… several built-in functions for rounding: Math.floor Rounds down: 3.1 becomes 3, and -1.1 becomes -2.… -1 -1 -1 -1.5 -2 -1 -1 -1 -1.6 -2 -1 -2 -1 These functions cover all of the possible ways to deal… For instance, we have 1.2345 and want to round it to 2 digits, getting only 1.23.… It ensures that it has 2 digits after the decimal point.

…But please note: the example above shows 1, then 2, and that’s all. It doesn’t show 3!… It starts the execution and returns the result of the first yield "2+2=?".… For instance, here the yield of "2 + 2 = ?… The error, thrown into the generator at line (2)… The current line of the calling code is the line with generator.throw, labelled as (2).

For example, the pattern \b\d\d\b looks for standalone 2-digit numbers.… In other words, it looks for 2-digit numbers that are surrounded by characters different from \w, such

Response provides multiple promise-based methods to access the body in various formats: response.text

For compatibility, 2 digits are also accepted and considered 19xx, e.g. 98 is the same as 1998 here,… It returns 2-digit year sometimes. Please never use it. There is getFullYear() for the year.… Let’s say we need to increase the date “28 Feb 2016” by 2 days.… It may be “2 Mar” or “1 Mar” in case of a leap-year. We don’t need to think about it.… Just add 2 days.

They both call func with arguments 1, 2… So when worker.slow(2) is executed, the wrapper gets 2 as an argument and this=worker (it’s the object… is not yet cached, func.call(this, x) passes the current this (=worker) and the current argument (=2)… Append glue and this[2]. …Do so until this.length items are glued. Return result.

Solution 2: bind.Functions provide a built-in method bind that allows to fix this.… The call to mul.bind(null, 2)… creates a new function double that passes calls to mul, fixing null as the context and 2 as the first

We can open it with version 2 and perform the upgrade like this:… And it can’t be both version 1 and 2.… from 2 to 3, from 3 to 4 etc.… by step, for every intermediate version (2 to 3, then 3 to 4).… Get the store object using transaction.objectStore(name), at (2).

symbols.There exist many “system” symbols that JavaScript uses internally, and we can use them to fine-tune various

Indents.There are two types of indents: Horizontal indents: 2 or 4 spaces.… A horizontal indentation is made using either 2 or 4 spaces or the horizontal tab symbol (key Tab).… Option 1: Option 2:

Here space = 2 tells JavaScript to show nested objects on multiple lines, with indentation of 2 spaces… Now let’s add a custom toJSON for our object room (2):

state event.button Left button (primary) 0 Middle button (auxiliary) 1 Right button (secondary) 2… (forward) 4 Most mouse devices only have the left and right buttons, so possible values are 0 or 2.… non-standard way of getting a button, with possible values: event.which == 1 – left button, event.which == 2

As we can see, there are 2

Assignments There is a simple assignment: a = b and combined ones like a *= 2.… Parameters can have default values: function sum(a = 1, b = 2) {...}.

For 2 the second alert runs.

Similar to that, \2 would mean the contents of the second group, \3 – the 3rd group, and so on.

We can put anything in there: a variable like name or an arithmetical expression like 1 + 2 or something… Usually, such parentheses contain a mathematical expression, such as (2 + 2), but here they contain only

Uint16Array – treats every 2 bytes as an integer, with possible values from 0 to 65535.… binary data in an ArrayBuffer of 16 bytes can be interpreted as 16 “tiny numbers”, or 8 bigger numbers (2… bytes each), or 4 even bigger (4 bytes each), or 2 floating-point values with high precision (8 bytes

In the code above: We load 1.js, then if there’s no error… We load 2.… loadScript('2.js', function(error, script) { if (error) { handleError(error); } else

Parentheses can be omitted, if there’s only a single argument, e.g. n => n*2.

The order became 1, 15, 2. Incorrect. But why? The items are sorted as strings by default.… For strings, lexicographic ordering is applied and indeed "2" > "15".… The function passed to reduce uses only 2… On the second run, sum = 1, we add the second array element (2) to it and return.… call on the next array element: sum current result the first call 0 1 1 the second call 1 2

: offsetWidth = 390 – the outer width, can be calculated as inner CSS-width (300px) plus paddings (2… * 20px) and borders (2 * 25px). offsetHeight = 290 – the outer height.… so it’s exactly the sum of what’s inside the borders: CSS-height 200px plus top and bottom paddings (2

That’s not reliable, because the input can come from various sources.

is: if we have two elements, the first has tabindex="1", and the second has tabindex="2&… The order is like this: 1 - 2

That’s why (2) null == 0 is false.… We get these results because: Comparisons (1) and (2) return false because undefined gets converted

For instance, the Promise.all below settles after 3 seconds, and then its result is an array [1, 2, 3… For instance, here the results are [1, 2, 3]:

Full example.Here’s the server that sends messages with 1, 2,… connection state: either EventSource.CONNECTING (=0), EventSource.OPEN (=1) or EventSource.CLOSED (=2)

The first number \d+ has 7 digits, and then a number of 2 digits:… The first number has 6 digits, and then 2… Here \2

Please note: the division 5/2

The output order is: 1 → nested → 2.… The output order becomes: 1 → 2 → nested.

The ending point also has <p> as the parent node, but 2 as the offset (it specifies the range up… So we can set it as range.setEnd(p, 2). Here’s the demo.… We need to create a range, that: starts from position 2 in <p> first child (taking all but two… startOffset – node and offset of the start, in the example above: first text node inside <p> and 2.