JavaScript: l'oggetto Strings

Il Stringobject ti permette di lavorare con una serie di personaggi; avvolge il tipo di dati primitivo stringa di Javascript con un numero di metodi di supporto.

Poiché JavaScript converte automaticamente tra primitive stringa e oggetti String, è possibile chiamare uno qualsiasi dei metodi di supporto dell'oggetto String su una primitiva stringa.

Sintassi

Utilizzare la seguente sintassi per creare un oggetto String:

var val = new String(string);

Il String parametro è una serie di caratteri che sono stati codificati correttamente.

Proprietà stringa

Di seguito è riportato un elenco delle proprietà dell'oggetto String e la loro descrizione.

Sr.No. Proprietà e descrizione
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.