JavaScript Data Types & Data Structures Flashcards

The symbol data type represents a unique identifier in JavaScript. Symbols are often used as keys in objects to prevent naming conflicts. Here is an example code for using the symbol data type:

/* Symbol */
let mySymbol = Symbol("mySymbol");
console.log(mySymbol);

The map data type represents a collection of key-value pairs in JavaScript. Maps are similar to objects, but they can use any data type as a key and maintain the order of insertion. Here is an example code for using the map data type:

/* Map */
let myMap = new Map();
myMap.set("name", "John");
myMap.set("age", 30);
console.log(myMap.get("name"));

The array data type represents a collection of values in JavaScript. Arrays can contain any data type, including other arrays and objects. Here is an example code for using the array data type:

/* Array */
let myArray = [1, 2, 3, "four", true, [5, 6, 7]];
console.log(myArray);

The boolean data type represents true or false values in JavaScript. Here is an example code for using the boolean data type:

/* Boolean */
let myBoolean = true;
console.log(myBoolean);

The string data type represents a sequence of characters in JavaScript. Here is an example code for using the string data type:

/* String */
let myString = "Hello, world!";
console.log(myString);

The undefined data type represents a variable that has been declared but not assigned a value. Here is an example code for using the undefined data type:

/* Undefined */
let myUndefined;
console.log(myUndefined);

The bigint data type represents integers that are larger than the maximum safe integer size in JavaScript. BigInts can be created by appending the letter n to the end of an integer literal. Here is an example code for using the bigint data type:

/* BigInt */
let myBigInt = 12345678901234567890n;
console.log(myBigInt);

The weakmap and weakset data types are similar to the map and set data types, but they allow the garbage collector to reclaim their memory if the only references to their keys or values are weak references. WeakMap and WeakSet can be useful for managing memory in large applications. Here is an example code for using the weakmap and weakset data types:

/* WeakMap and WeakSet */
let myWeakMap = new WeakMap();
let myObject = {};
myWeakMap.set(myObject, "value");
console.log(myWeakMap.get(myObject));

let myWeakSet = new WeakSet();
let myObject2 = {};
myWeakSet.add(myObject2);
console.log(myWeakSet.has(myObject2));

The object data type represents a collection of key-value pairs in JavaScript. Objects can contain other objects, arrays, and functions. Here is an example code for using the object data type:

/* Object */
let myObject = {
  name: "John",
  age: 30,
  address: {
    street: "123 Main St",
    city: "Anytown",
    state: "CA",
  },
};
console.log(myObject);

The null data type represents a variable that has been explicitly assigned a null value. Here is an example code for using the null data type:

/* Null */
let myNull = null;
console.log(myNull);

The function represents a block of code that can be called with zero or more arguments. Functions can be defined using function declarations, function expressions, or arrow functions. Here is an example code for using the function:

/* Function */
function myFunction(x, y) {
  return x + y;
}

console.log(myFunction(2, 3));

The set data type represents a collection of unique values in JavaScript. Sets can contain any data type and maintain the order of insertion. Here is an example code for using the set data type:

/* Set */
let mySet = new Set();
mySet.add(1);
mySet.add(2);
mySet.add(2); // ignored
console.log(mySet);

The date represents a specific date and time in JavaScript. Dates can be created using the Date constructor, which takes the year, month, day, hour, minute, second, and millisecond as arguments. Here is an example code for using the date:

/* Date */
let myDate = new Date();
console.log(myDate);

The number data type represents both integer and floating point numbers in JavaScript. Here is an example code for using the number data type:

/* Number */
let myNumber = 42;
console.log(myNumber);

The regexp represents a regular expression in JavaScript. Regular expressions are used to match patterns in strings. Regexp can be created using the RegExp constructor or using a regular expression literal. Here is an example code for using the regexp:

/* RegExp */
let myRegExp = /hello/;
console.log(myRegExp.test("Hello, world!")); // false
console.log(myRegExp.test("hello, world!")); // true