How to Use Text Processing with Strings

Instance methods

String.prototype.at()

Returns the character (exactly one UTF-16 code unit) at the specified index. Accepts negative integers, which count back from the last string character.

String.prototype.charAt()

Returns the character (exactly one UTF-16 code unit) at the specified index.

String.prototype.charCodeAt()

Returns a number that is the UTF-16 code unit value at the given index.

String.prototype.codePointAt()

Returns a nonnegative integer Number that is the code point value of the UTF-16 encoded code point starting at the specified pos.

String.prototype.concat()

Combines the text of two (or more) strings and returns a new string.

String.prototype.endsWith()

Determines whether a string ends with the characters of the string searchString.

String.prototype.includes()

Determines whether the calling string contains searchString.

String.prototype.indexOf()

Returns the index within the calling String object of the first occurrence of searchValue, or -1 if not found.

String.prototype.isWellFormed()

Returns a boolean indicating whether this string contains any lone surrogates.

String.prototype.lastIndexOf()

Returns the index within the calling String object of the last occurrence of searchValue, or -1 if not found.

String.prototype.localeCompare()

Returns a number indicating whether the reference string compareString comes before, after, or is equivalent to the given string in sort order.

String.prototype.match()

Used to match regular expression regexp against a string.

String.prototype.matchAll()

Returns an iterator of all regexp's matches.

String.prototype.normalize()

Returns the Unicode Normalization Form of the calling string value.

String.prototype.padEnd()

Pads the current string from the end with a given string and returns a new string of the length targetLength.

String.prototype.padStart()

Pads the current string from the start with a given string and returns a new string of the length targetLength.

String.prototype.repeat()

Returns a string consisting of the elements of the object repeated count times.

String.prototype.replace()

Used to replace occurrences of searchFor using replaceWith. searchFor may be a string or Regular Expression, and replaceWith may be a string or function.

String.prototype.replaceAll()

Used to replace all occurrences of searchFor using replaceWith. searchFor may be a string or Regular Expression, and replaceWith may be a string or function.

String.prototype.search()

Search for a match between a regular expression regexp and the calling string.

String.prototype.slice()

Extracts a section of a string and returns a new string.

String.prototype.split()

Returns an array of strings populated by splitting the calling string at occurrences of the substring sep.

String.prototype.startsWith()

Determines whether the calling string begins with the characters of string searchString.

String.prototype.substr() Deprecated

Returns a portion of the string, starting at the specified index and extending for a given number of characters afterwards.

String.prototype.substring()

Returns a new string containing characters of the calling string from (or between) the specified index (or indices).

String.prototype.toLocaleLowerCase()

The characters within a string are converted to lowercase while respecting the current locale.

For most languages, this will return the same as toLowerCase().

String.prototype.toLocaleUpperCase()

The characters within a string are converted to uppercase while respecting the current locale.

For most languages, this will return the same as toUpperCase().

String.prototype.toLowerCase()

Returns the calling string value converted to lowercase.

String.prototype.toString()

Returns a string representing the specified object. Overrides the Object.prototype.toString() method.

String.prototype.toUpperCase()

Returns the calling string value converted to uppercase.

String.prototype.toWellFormed()

Returns a string where all lone surrogates of this string are replaced with the Unicode replacement character U+FFFD.

String.prototype.trim()

Trims whitespace from the beginning and end of the string.

String.prototype.trimEnd()

Trims whitespace from the end of the string.

String.prototype.trimStart()

Trims whitespace from the beginning of the string.

String.prototype.valueOf()

Returns the primitive value of the specified object. Overrides the Object.prototype.valueOf() method.

String.prototype[@@iterator]()

Returns a new iterator object that iterates over the code points of a String value, returning each code point as a String value.

HTML wrapper methods

Warning: Deprecated. Avoid these methods.

They are of limited use, as they are based on a very old HTML standard and provide only a subset of the currently available HTML tags and attributes. Many of them create deprecated or non-standard markup today. In addition, they do simple string concatenation without any validation or sanitation, which makes them a potential security threat when directly inserted using innerHTML. Use DOM APIs such as document.createElement() instead.

String.prototype.anchor() Deprecated: <a name="name"> (hypertext target)
String.prototype.big() Deprecated: <big>
String.prototype.blink() Deprecated: <blink>
String.prototype.bold() Deprecated: 
String.prototype.fixed() Deprecated: <tt>
String.prototype.fontcolor() Deprecated: 
String.prototype.fontsize() Deprecated: 
String.prototype.italics() Deprecated: 
String.prototype.link() Deprecated: <a href="url"> (link to URL)
String.prototype.small() Deprecated: 
String.prototype.strike() Deprecated: <strike>
String.prototype.sub() Deprecated: 
String.prototype.sup() Deprecated:

Note that these methods do not check if the string itself contains HTML tags, so it's possible to create invalid HTML:

"</b>".bold(); // <b></b></b>

The only escaping they do is to replace " in the attribute value (for anchor(), fontcolor(), fontsize(), and link()) with ".

"foo".anchor('"Hello"'); // <a name="&quot;Hello&quot;">foo</a>