Hướng dẫn javascript array math operations
It does, but that
the value of Simply use the result:
Updated snippet: Of course, this means your
Just FWIW, there's a clever way to update
That'll wrap around for you. This chapter introduces the concepts, objects and functions used to work with and perform calculations using numbers and dates in JavaScript. This includes using numbers
written in various bases including decimal, binary, and hexadecimal, as well as the use of the global In JavaScript, numbers are implemented in double-precision 64-bit binary format IEEE 754 (i.e., a number between ±2^−1022 and ±2^+1023, or about ±10^−308 to ±10^+308, with a numeric precision of 53 bits). Integer values
up to ±2^53 − 1 can be represented exactly. In addition to being able to represent floating-point numbers, the number type has three symbolic values: See also JavaScript data types and structures for context with other primitive types in JavaScript. You can use four types of number literals: decimal, binary, octal, and hexadecimal. Note that decimal literals can start with a zero ( Binary numbersBinary number syntax uses a leading zero followed by a lowercase or uppercase Latin letter "B" (
Octal numbersThe standard syntax for octal numbers
is to prefix them with There's also a legacy syntax for octal numbers — by prefixing the octal number with a zero:
Strict mode forbids this octal syntax. Hexadecimal numbersHexadecimal number syntax uses a leading zero followed by a lowercase or uppercase Latin letter "X" (
Exponentiation
Number objectThe built-in
You always refer to a property of the predefined The following table summarizes the The Math objectThe built-in Similarly, standard mathematical functions are methods of Note that all trigonometric methods of The following table summarizes the Unlike many other
objects, you never create a BigIntsOne shortcoming of number values is they only have 64 bits. In practice, due to using IEEE 754 encoding, they cannot represent any integer larger than
A BigInt can be defined as an integer literal suffixed by
BigInts can also be constructed from number values or string values using the
Conceptually, a BigInt is just an arbitrarily long sequence of bits which encodes an integer. You can safely do any arithmetic operations without losing precision or over-/underflowing.
Compared to numbers, BigInt values yield higher precision when representing large integers; however, they cannot represent floating-point numbers. For example, division would round to zero:
Choosing between BigInt and number depends on your use-case and your input's range. The precision of numbers should be able to accommodate most day-to-day tasks already, and BigInts are most suitable for handling binary data. Read more about what you can do with BigInt values in the Expressions and Operators section, or the BigInt reference. Date objectJavaScript does not have a date data type. However, you can use the JavaScript handles dates similarly to Java. The two languages have many of the same date methods, and both languages store dates as the number of milliseconds since January 1, 1970, 00:00:00, with a Unix Timestamp being the number of seconds since January 1, 1970, 00:00:00. The To create a
where Calling The
Methods of the Date objectThe
With the "get" and "set" methods you can get and set seconds, minutes, hours, day of the month, day of the week, months, and years separately. There is a
For example, suppose you define the following date:
Then The For example, the following code displays the number of days left in the current year:
This example creates a The
ExampleIn the following example, the function
The The next four statements build a string value based on the time. The first statement creates a variable The next statement appends a Finally, a conditional expression appends "P.M." to
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