ジャバスクリプト
JavaScriptにも説明したデータ型があります.
最も使用されるデータ型は、数字と文字列/テキストです.
私はすでに詳細に番号をカバーしています.
この記事ではJavaScriptの文字列/テキストデータ型を詳細に表示します.
あなたの名前をいくつかの変数に格納したい場合は、各文字を別の変数に格納するか、配列内のすべての文字を格納するのは難しいでしょう.
C言語は文字列を表す文字列を使用します.
JavaScriptは文字列、つまり文字列を表すデータ型を別々に提供します.
JavaScriptの文字列は何ですか？
文字列は16ビット値の不変のシーケンスで、それぞれがUnicode文字を表します.
JavaScriptの文字列(およびその配列)はゼロベースのインデックスを使用します.
第1の16ビット値は位置0、位置1の第2の16ビット、その他で表される.
では文字列の長さは何ですか？
JavaScript文字列長は、それが含む16ビットの値の数として計算されます.
注意:
JavaScriptは単一の16ビット値を表す特定のデータ型を持っていません.
これを長さ1の文字列で表す.
Javascript uses the UTF-16 encoding of the Unicode character set.
The most commonly used Unicode characters are fit into 16-bit and can be represented by a single element.
Unicode characters that don’t fit into 16-bit are encoded using rules of UTF-16 as a sequence(known as “Surrogate pair”) of two 16-bit values. This means JavaScript string with a single character may return length as 2.
Example:-
let dollar = “$”;
let emoji = “🤘”;
dollar.length; // 1
emoji.length; // 2
文字列リテラル
JavaScriptプログラムに直接文字列を使用するには、単一の/二重引用符の一致するペア内で文字列の文字を囲むだけです.
ES 6 JavaScriptでは、より単純な方法でストリングを表すためにbackticks (`)を提供しました.
例:
‘Hello Devs’
“I’m Ganesh.”
The original version of JavaScript required string literals to be written on a single line. And to create a long string it is common to concatenating string using the + operator.
As of ES5, you can break the string into multiple lines by adding a backslash() at the end of the line.
The ES6 made it easier for devs to write a string into multiple lines with backticks, without adding any special characters like(\n).
Examples:-
“Long \
string \
With ES5”
文字列リテラルのエスケープシーケンス
The backslash character () has a special purpose in Javascript strings. Combined
with the character that follows it, it represents a character that is not otherwise representable within the string.
The backslash () allows you to escape from the usual interpretation of the single-quotes character. Instead of using it as the end of the string, you use it as a single quote.
Example:-
‘Hello, dev\’s you\’re Awesome.’ // => Hello, dev’s you’re Awesome.
A table that represents JavaScript escape sequence.
文字列の操作
If we use the + operator with numbers it adds them, but using the + operator on string results in concatenating 2 strings.
let text = “Hello ” + “world!!!!”;
A string can be compared with ===(equality) or !==(inequality) operators, two strings are equal if they consist of exactly the same sequence of 16-bit values.
A string can also be compared with the <, <=, >, and >= operators.
String comparison is done simply by comparing the 16-bit values.
As I mentioned before the length of a string is the number of 16-bit values it contains.
JavaScript provides a rich API for working with string.
`
let str = "Hello, JavaScript Lovers.";
// Getting portion of the string
str.substring(1, 8); // "ello, J" charates from 1 to 8
str.slice(1, 8); // "ello, J" charates from 1 to 8
str.slice(-4); // "ers." last 4 characters
str.split(','); // ["Hello", " JavaScript Lovers."]
// Searching a string
str.indexOf('J'); // 7 Position of first “J”
str.indexOf('44'); // -1 “44” not present in str
str.lastIndexOf('l'); // 3 Position of “l” from last
// Searching function of ES6 and later
str.startsWith('He'); // true Checks if string starts with “He”
str.endsWith('He'); // false Checks if string ends with “He”
str.includes('JavaScript'); // true Checks if string contains “JavaScript”
// Modifying string
str.replace('JavaScript', 'tea'); // "Hello, tea Lovers." Replaces the maching part of string
str.toLowerCase(); // "hello, javascript lovers." Converts string to lower case
str.toUpperCase(); // "HELLO, JAVASCRIPT LOVERS." Converts string to upper case
// Inspecting individual 16-bit characters of string
str.charAt(0); // “H” Returns character at position 0
str.charAt(str.length - 2); // “s” Getting 2nd last character of string
str.charCodeAt(0); // 72 16-bit number at position 0
str.codePointAt(0); // 72 ES6 - this world for codepoints > 16-bits
// String padding functions in ES2017
"xyz".padStart(6); // " xyz" add spaces on the left of string and make length 6
"xyz".padEnd(6); // "xyz " add spaces on the righ of string and make length 6
"xyz".padStart(6, "#"); // "###xyz" add # as padding
"xyz".padEnd(6, "#"); // "xyz###" add # as padding
// Space trimming functions trim() of ES5 and others from ES2019
" xyz ".trim(); // "xyz" Removes empty spaces from start and end
" xyz ".trimStart(); // "xyz " Removes empty spaces from start
" xyz ".trimEnd(); // " xyz" Removes empty spaces from end
// More string methods
str.concat("!!"); // "Hello, JavaScript Lovers.!!" Same as + operator
"=".repeat(5); // "=====" Repetes characters n times
`
注意:
JavaScript Strings are immutable. Methods like replace() or toUpperCase() returns new string with resulting value.
テンプレートリテラル
In Es6 and later, strings are represented using backticks.
let str =;
This is more than just another string literal syntax.
Template literals can include arbitrary javascript expression. The final value of string literal in backtick is computed by evaluating any included expression, converting the values of those expressions to a string.
Example:-
// "Addition of 2 + 4 is 6."
That’s it for the strings in JavaScript.
I hope you liked this article.
In the next article of this series, I will be covering Expressions and operators part-1.
Hope you like it, if yes **like & share.**
Thanks for your time.
Happy coding….
Reference
この問題について(ジャバスクリプト), 我々は、より多くの情報をここで見つけました https://dev.to/ganeshjaiwal/javascript-strings-a00テキストは自由に共有またはコピーできます。ただし、このドキュメントのURLは参考URLとして残しておいてください。
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