JavaScript-文字列オブジェクト

ザ・ Stringオブジェクトを使用すると、一連の文字を操作できます。Javascriptの文字列プリミティブデータ型をいくつかのヘルパーメソッドでラップします。

JavaScriptは文字列プリミティブとStringオブジェクトの間で自動的に変換するため、文字列プリミティブでStringオブジェクトの任意のヘルパーメソッドを呼び出すことができます。

構文

次の構文を使用して、Stringオブジェクトを作成します-

var val = new String(string);

ザ・ String パラメータは、適切にエンコードされた一連の文字です。

文字列のプロパティ

Stringオブジェクトのプロパティとその説明のリストを次に示します。

シニア番号	プロパティと説明
1	constructor Returns a reference to the String function that created the object.
2	length Returns the length of the string.
3	prototype The prototype property allows you to add properties and methods to an object.

In the following sections, we will have a few examples to demonstrate the usage of String properties.

String Methods

Here is a list of the methods available in String object along with their description.

Sr.No.	Method & Description
1	charAt() Returns the character at the specified index.
2	charCodeAt() Returns a number indicating the Unicode value of the character at the given index.
3	concat() Combines the text of two strings and returns a new string.
4	indexOf() Returns the index within the calling String object of the first occurrence of the specified value, or -1 if not found.
5	lastIndexOf() Returns the index within the calling String object of the last occurrence of the specified value, or -1 if not found.
6	localeCompare() Returns a number indicating whether a reference string comes before or after or is the same as the given string in sort order.
7	match() Used to match a regular expression against a string.
8	replace() Used to find a match between a regular expression and a string, and to replace the matched substring with a new substring.
9	search() Executes the search for a match between a regular expression and a specified string.
10	slice() Extracts a section of a string and returns a new string.
11	split() Splits a String object into an array of strings by separating the string into substrings.
12	substr() Returns the characters in a string beginning at the specified location through the specified number of characters.
13	substring() Returns the characters in a string between two indexes into the string.
14	toLocaleLowerCase() The characters within a string are converted to lower case while respecting the current locale.
15	toLocaleUpperCase() The characters within a string are converted to upper case while respecting the current locale.
16	toLowerCase() Returns the calling string value converted to lower case.
17	toString() Returns a string representing the specified object.
18	toUpperCase() Returns the calling string value converted to uppercase.
19	valueOf() Returns the primitive value of the specified object.

String HTML Wrappers

Here is a list of the methods that return a copy of the string wrapped inside an appropriate HTML tag.

Sr.No.	Method & Description
1	anchor() Creates an HTML anchor that is used as a hypertext target.
2	big() Creates a string to be displayed in a big font as if it were in a <big> tag.
3	blink() Creates a string to blink as if it were in a <blink> tag.
4	bold() Creates a string to be displayed as bold as if it were in a <b> tag.
5	fixed() Causes a string to be displayed in fixed-pitch font as if it were in a <tt> tag
6	fontcolor() Causes a string to be displayed in the specified color as if it were in a <font color="color"> tag.
7	fontsize() Causes a string to be displayed in the specified font size as if it were in a <font size="size"> tag.
8	italics() Causes a string to be italic, as if it were in an <i> tag.
9	link() Creates an HTML hypertext link that requests another URL.
10	small() Causes a string to be displayed in a small font, as if it were in a <small> tag.
11	strike() Causes a string to be displayed as struck-out text, as if it were in a <strike> tag.
12	sub() Causes a string to be displayed as a subscript, as if it were in a <sub> tag
13	sup() Causes a string to be displayed as a superscript, as if it were in a <sup> tag

In the following sections, we will have a few examples to demonstrate the usage of String methods.