JS String

Question 1

How can you access a character in a string?

Answer 1

A) ‘dog’.charAt(1) // “o”

B) ‘dog’[2] // “g”

Question 2

How can primitive strings use methods of the object String without the ‘new’ keyword?

Answer 2

JavaScript will automatically wrap the string primitive and call the method or perform the property lookup on the wrapper object instead.

Question 3

\0

Answer 3

Escape sequence null character (U+0000 NULL)

Question 4

' " \

Answer 4

Escape sequences
single quote (U+0027 APOSTROPHE)
double quote (U+0022 QUOTATION MARK)\
backslash (U+005C REVERSE SOLIDUS)

Question 5

\n \r \b

Answer 5

Escape sequences
newline (U+000A LINE FEED; LF)
carriage return (U+000D CARRIAGE RETURN; CR)
backspace (U+0008 BACKSPACE)

Question 6

\v \t \f

Answer 6

Escape sequences
backslash vertical tab (U+000B LINE TABULATION)
tab (U+0009 CHARACTER TABULATION)
form feed (U+000C FORM FEED)

Question 7

\uXXXX

Answer 7

escape sequence
Unicode code point between U+0000 and U+FFFF
(the Unicode Basic Multilingual Plane)

Question 8

String.prototype.length

Answer 8

a read only property, returns the length of the string

Question 9

String.prototype.charAt(index)

String.prototype.charCodeAt(index)

String.prototype.indexOf(searchValue [, fromIndex])

String.prototype.lastIndexOf(searchValue [, fromIndex])

Answer 9

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

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

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

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

Question 10

String.prototype.concat(str [, …strN ])

Answer 10

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

Question 11

String.prototype.includes(searchString [, position])

String.prototype.endsWith(searchString [, length])

String.prototype.startsWith(searchString [, length])

Answer 11

Determines whether the calling string contains searchString.

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

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

Question 12

String.prototype.localeCompare(compareString [, locales [, options]])

Answer 12

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

Question 13

String.prototype.matchAll(regexp)

String.prototype.match(regexp)

String.prototype.search(regexp)

Answer 13

Returns an iterator of all regexp’s matches.

Used to match regular expression regexp against a string.

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

Question 14

String.prototype.padEnd(targetLength [, padString])

String.prototype.padStart(targetLength [, padString])

Answer 14

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

Question 15

String.prototype.repeat(count)

Answer 15

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

Question 16

String.prototype.replace(searchFor, replaceWith)

String.prototype.replaceAll(searchFor, replaceWith)

Answer 16

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

Question 17

String.prototype.slice(beginIndex[, endIndex])

String.prototype.substring(indexStart [, indexEnd])

Answer 17

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

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

Question 18

String.prototype.split([sep [, limit] ])

const array = […string]

Answer 18

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

Question 19

String.prototype.toLocaleLowerCase( [locale, …locales])

String.prototype.toLocaleUpperCase( [locale, …locales])

Answer 19

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

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

Question 20

String.prototype.trim()

String.prototype.trimStart()

String.prototype.trimEnd()

Answer 20

Trims whitespace from the beginning and end of the string.

Question 21

parseInt()

Answer 21

The parseInt() function parses a string argument and returns an integer of the specified radix (the base in mathematical numeral systems).

Question 22

parseFloat()

Answer 22

The parseFloat() function parses an argument (converting it to a string first if needed) and returns a floating point number.