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Questions and Answers
What will be the returned value of myStr.charAt(0)?
What will be the returned value of myStr.charAt(0)?
What will be the result of myStr.split(' ', 3)?
What will be the result of myStr.split(' ', 3)?
What does the method myStr.charCodeAt(12) return?
What does the method myStr.charCodeAt(12) return?
What is the output of the method myStr.replace(/e/g, '?!')?
What is the output of the method myStr.replace(/e/g, '?!')?
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Which method would you use to join multiple strings into one?
Which method would you use to join multiple strings into one?
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What value is returned by the method myStr.lastIndexOf('a')?
What value is returned by the method myStr.lastIndexOf('a')?
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When using the big method on the string 'hi', what is the expected output?
When using the big method on the string 'hi', what is the expected output?
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Study Notes
JavaScript Functions and Objects
- JavaScript functions and objects are fundamental building blocks in JavaScript.
- A JavaScript function is a block of code designed to perform a particular task.
String Object Methods
- Methods manipulate the contents of the String Object.
-
charAt(): returns the character at a specific index. -
charCodeAt(): Returns the Unicode value of a character at a specific index. -
split(): Splits a string into an array of substrings. -
indexOf(): Returns the index of the first occurrence of a substring. -
lastIndexOf(): Returns the index of the last occurrence of a substring. -
substring(): Extracts a portion of a string. -
concat(): Concatenates strings. -
replace(): Replaces occurrences of a part of a string with another. e.g.,replace(/e/,"?"). The/e/represents a search for the letter 'e' and the?represents the replacement character
String Appearance Methods
- Methods that manipulate the appearance of a String object.
- Methods include
big(),bold(),fontcolor(),fontsize(),italics(),small(),strike(), andsup(). - These methods are used to format text. e.g.,
hi".big(), returns<BIG>hi</BIG>.
Other Useful String Methods
-
toLowerCase(): Converts the string to lowercase -
toUpperCase(): Converts the string to uppercase -
endsWith(): Checks if a string ends with a specified substring. -
startsWith(): Checks if a string starts with a specified substring. -
includes(): Checks if a string contains a specified substring. -
repeat(): Repeats a string a specified number of times. -
search(): Searches for a specified substring and returns its index. -
trim(): Removes whitespace from both ends of a string. -
trimRight(): Removes whitespace from the right end of a string. -
trimLeft(): Removes whitespace from the left end of a string.
JavaScript and Databases:
- JavaScript can interact with databases in two ways:
- Client-side (browser): It utilizes local storage for small data amounts or communicates with a server for database access.
- Server-side (Node.js): Uses Node.js to directly connect to and manipulate databases.
Local Storage
- A simple key-value storage mechanism in a web browser.
- Data is persistently stored but limited to the same domain (origin).
IndexedDB
- A low-level API for managing large amounts of structured data in a web browser.
- Supports transactions and indexing for efficient querying.
Number Object
-
Number objects are not primitive; using number methods on primitives will convert them to Number objects behind the scenes.
-
Object wrappers for primitive numeric values.
-
Creating a Number object:
var n = new Number(101); OR n = new Number(); // if not initialized, it will be 0. -
Number object class constant values:
Number.MAX_VALUE,Number.MIN_VALUE,Number.NaN,Number.POSITIVE_INFINITY,Number.NEGATIVE_INFINITY. -
Number object methods:
toFixed()(fixed-point representation),toExponential(),toPrecision(),toString(),valueOf(),toLocaleString().
Number Object Methods
-
toFixed(): Returns a string representing a number in fixed-point notation. -
toExponential(): Returns a string representing a number in exponential notation. -
toPrecision(): Returns a string representing a number to the specified precision. -
toString(): Converts a number to a string (e.g.,toString(16)for hexadecimal). -
valueOf(): Returns the primitive value of a Number object. -
toLocaleString(): Returns a string representation of the number with locale-specific formatting.
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Description
This quiz tests your knowledge of JavaScript functions and string object methods. You'll learn about the fundamental building blocks of JavaScript, including various methods to manipulate strings. Perfect for anyone looking to enhance their programming skills in JavaScript.
