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There are four logical operators in JavaScript: || (OR), && (AND), ! (NOT), ??… operator is in the next article.… In JavaScript, the operator is a little bit trickier and more powerful.… Another feature of OR || operator is the so-called “short-circuit” evaluation.… (NOT).The boolean NOT operator is represented with an exclamation sign !.

We know many operators from school.… that share the same symbol: the negation operator, a unary operator that reverses the sign, and the… subtraction operator, a binary operator that subtracts one number from another.… There are many operators in JavaScript. Every operator has a corresponding precedence number.… Comma.The comma operator , is one of the rarest and most unusual operators.

The nullish coalescing operator is written as two question marks ??.… The nullish coalescing operator isn’t anything completely new.… On the other hand, the nullish coalescing operator ??… , but after most other operations, such as +, *.… The nullish coalescing operator ??

That can be done using constructor functions and the "new" operator.… They should be executed only with "new" operator.

To do that, we can use the if statement and the conditional operator ?… , that’s also called a “question mark” operator.… The operator is represented by a question mark ?.… It’s not recommended to use the question mark operator in this way.… The purpose of the question mark operator ?

Conditional The only operator with three parameters: cond ? resultA : resultB.… Nullish coalescing operator The ??… operator provides a way to choose a defined value from a list of variables. The result of a ??… Other operators There are few others, like a comma operator.… More in: Basic operators, maths, Comparisons, Logical operators, Nullish coalescing operator '??'.

All operations on bigints return bigints.… The conversion operations… The unary plus is not supported on bigints The unary plus operator +value is a well-known… The reason is that many JavaScript operators, such as +, - and so on behave differently with bigints… We can use them instead of native bigints: Operation native BigInt JSBI Creation from Number a

a chance to handle it, otherwise the operation is performed on target.… A writing operation proxy.test= sets the value on target.… A reading operation proxy.test returns the value from target.… Here are examples of operations and Reflect calls that do the same: Operation Reflect call Internal… The new operator (construct trap).

JavaScript doesn’t allow you to customize how operators work on objects.… In case of such operations, objects are auto-converted to primitives, and then the operation is carried… That’s an important limitation: the result of obj1 + obj2 (or another math operation) can’t be another… There are exceptions, where such operations are possible and look good.… "default" Occurs in rare cases when the operator is “not sure” what type to expect.

Most of the time, operators and functions automatically convert the values given to them to the right… Mathematical operations convert values to numbers.… Most mathematical operators also perform such conversion, we’ll see that in the next chapter.… Numeric Conversion – Occurs in math operations. Can be performed with Number(value).… Boolean Conversion – Occurs in logical operations. Can be performed with Boolean(value).

On the last line there is a conditional operator… Reference type explained.Looking closely, we may notice two operations in obj.method() statement: First… If we put these operations on separate lines, then this will be lost for sure:… So any further operation “loses” this.… For all other operations, the reference type automatically becomes the property value (a function in

There are many operations for numbers, e.g. multiplication *, division /, addition +, subtraction -,… Mathematical operations are safe Doing maths is “safe” in JavaScript.… The typeof operator.The typeof operator returns the type of the operand.… To put it clear: typeof is an operator, not a function.… The typeof operator allows us to see which type is stored in a variable.

Arrays support both operations. In practice we need it very often.… The shift operation must do 3 things: Remove the element with the index 0.… The more elements in the array, the more time to move them, more in-memory operations.… The == operator doesn’t do item-by-item comparison.… That’s simple: don’t use the == operator.

We know many comparison operators from maths.… Boolean is the result.All comparison operators return a boolean value: true – means “yes”, “correct”… A strict equality operator === checks the equality without type conversion.… The strict equality operator is a bit longer to write, but makes it obvious what’s going on and leaves… Comparison operators return a boolean value.

JavaScript before year 2020 didn’t have the “nullish coalescing operator” ??.… Polyfills.New language features may include not only syntax constructs and operators, but also built-in… Just don’t forget to use a transpiler (if using modern syntax or operators) and polyfills (to add functions

readAsDataURL(blob) – read the binary data and encode it as base64 data url. abort() – cancel the operation… readAsArrayBuffer – for binary files, to do low-level binary operations.… For high-level operations, like slicing, File inherits from Blob, so we can call them directly, without

That’s all possible in JavaScript, and binary operations are high-performant.… But if we’re going to write into it, or iterate over it, basically for almost any operation – we must… To do almost any operation on ArrayBuffer, we need a view.… In most cases we create and operate directly on typed arrays, leaving ArrayBuffer under cover, as a “… There are also two additional terms, that are used in descriptions of methods that operate on binary

A write operation to document.cookie updates only the cookie mentioned in it and doesn’t touch other… That’s because the document.cookie= operation does not overwrite all cookies.… They must not perform any data-changing operations.… The operation performs a top-level navigation (changes URL in the browser address bar).… Write operations modify only the cookie mentioned in it. Name/value must be encoded.

To remove a property, we can use the delete operator… Why does the in operator… So the in operator works right.… So the in operator is an exotic guest in the code.… Additional operators: To delete a property: delete obj.prop.

The obvious solution would be to check the value using if or the conditional operator ?… There’s a little better way to write it, using the && operator:… So, if there are any further function calls or operations to the right of ?., they won’t be made.… is not an operator, but a special syntax construct, that also works with functions and square brackets

Write/delete operations work directly with the object.… They only operate on the object itself. Properties from the prototype are not taken into account.… Write/delete operations act directly on the object, they don’t use the prototype (assuming it’s a data… All other key/value-getting methods only operate on the object itself.

The instanceof operator allows to check whether an object belongs to a certain class.… And instanceof operator really shines when we are working with a class hierarchy and want to check for

To unify error handling, we’ll use the throw operator.… “Throw” operator.The throw operator generates an error.… In the line (*), the throw operator… Usually, we can check the error type using the instanceof operator:… We can also generate our own errors using the throw operator.

For errors in network operations we may need HttpError, for database operations DbError, for searching… operations NotFoundError and so on.

Here we can rewrite the same using the conditional operator ?… The “delete element” and “insert element” operations are expensive.… For instance, arr.unshift(obj) operation has to renumber all elements to make room for a new obj, and… The only structural modifications that do not require mass-renumbering are those that operate with the… …But we don’t always need such operations.

A transaction is a group of operations, that should either all succeed or all fail.… It would be pretty bad if we complete the 1st operation, and then something goes wrong, e.g. lights out… All data operations must be made within a transaction in IndexedDB.… We can’t insert an async operation like fetch, setTimeout in the middle of a transaction.… Individual requests may succeed, but the final write operation may go wrong (e.g.

take a property user.name, the JavaScript engine looks at what’s at that address and performs the operation… All operations via copied references (like adding/removing properties) are performed on the same single

Generally, we have two parties in the process: The one that performs a cancelable operation, it sets

__proto__= is a very slow operation as it breaks internal optimizations for object property access operations

(Integrated Development Environment) refers to a powerful editor with many features that usually operates

for undefined: …Or using the || operator… …Or we could use the || operator… Modern JavaScript engines support the nullish coalescing operator

So we can operate… The style property operates only on the value of the "style" attribute, without any CSS cascade

Image operations are done via <canvas> element: Draw an image (or its part) on canvas using canvas.drawImage… That makes Blobs convenient for upload/download operations, that are so common in the browser.

If F.prototype is an object, then the new operator uses it to set [[Prototype]] for the new object.

Please note that syntax constructs that are not expressions cannot be used with the ternary operator… This is just another reason not to use the question mark operator ? instead of if.

setters.Getters/setters can be used as wrappers over “real” property values to gain more control over operations

Its purpose – is to provide the ability to perform additional operations, related to the object, after… For example: When the program fully terminates its operation (for example, when closing a tab in a browser… to remember, that such behavior is not guaranteed, and depends on the specific implementation and operation… This allows releasing resources associated with the object or performing other necessary operations before

base=2 is mostly for debugging bitwise operations, digits can be 0 or 1.… Rounding.One of the most used operations when working with numbers is rounding.… In most cases, the distinction is unnoticeable, because operators are suited to treat them as the same

Despite having the word “XML” in its name, it can operate on any data, not only in XML format.… The basics.XMLHttpRequest has two modes of operation: synchronous and asynchronous.

For instance: The navigator object provides background information about the browser and the operating

But the operation still won’t succeed.

But there’s a subtle difference between Array.from(obj) and [...obj]: Array.from operates on both array-likes

As we already know from the chapter Constructor, operator "new", new function can help with

let’s fetch and show a logo image of “fetch” specification (see chapter Blob for details about operations

The length property is sometimes used for introspection in functions that operate on other functions.

These methods operate exactly with what’s written in HTML.

Contains all the data about the operation (key/oldValue/newValue), the document url and the storage object

All operations on the DOM start with the document object. That’s the main “entry point” to DOM.

So if we want users of all operating systems to feel comfortable, then together with ctrlKey we should

If we make more complex editing operations