Numbers are used to represent both integer and floating-point values.
Numbers are most commonly expressed in literal forms like 255 or 3.14159 ↴
let num1 = 5; → number
let num2 = 2.5; → number
let num3 = num1 + num2;
console.log(num3); returns ↴
7.5 → number
Generate a fibonacci sequence up to n terms using ↴
recursion → programming technique where a function calls itself repeatedly to solve a problem.
for loop → executes a block of code a number of times.
Recursion The act of a function calling itself.
Recursion is used to solve problems that contain smaller sub-problems.
A recursive function can receive two inputs: a base case (ends recursion) or a recursive case (resumes recursion).
Use recursion to find the factorial of 5.
let x = 5;
function factorial(num) {
if (num > 1) { → Recursive call
return num * factorial(num - 1);
}
else { → Base case
return 1;
};
}
call function
factorial(x); returns ↴
120 factorial of 5 → 120
for loop repeatedly executes a block of code until a specified condition evaluates to false.
The loop runs a block of code a set number of times, defined by an initialization, a condition, and an increment.
for (let x = 0; x < 4; x++) {
console.log(x);
}
Loop variable x is initialized to 0
Condition x < 4 is checked before each iteration.
The loop will continue to run as long as x is less than 4
The loop repeatedly executes a block of code 4 times, from 0 to 3
For each iteration of the loop, the current value of x is printed to the console.
After each iteration, x is incremented by 1 x++
When x reaches 4 the condition evaluates to false, terminating the loop.
0
1
2
3 → printed to console
Initialize a variable to hold number of terms n to generate for a Fibonacci sequence.
const nTerms = n; → user input
Define a function fibonacci() to generate a Fibonacci sequence.
function fibonacci(nTerms) {}
The function takes a number as input nTerms and generates first n terms of the Fibonacci sequence.
Base case
nTerms if it is less than 2
if (nTerms < 2) {}
Return nTerms and end execution of function.
return nTerms
Recursive case
Function calls itself twice to compute the sum of the two preceding Fibonacci numbers.
return fibonacci(nTerms - 1) + fibonacci(nTerms - 2)
Print the header for the Fibonacci sequence.
console.log("Fibonacci Sequence:")
Initialize variable to store the nth Fibonacci term.
let nthTerm nthTerm
Loop through the range of terms and calculate Fibonacci numbers.
for (let x = 0; x < nTerms; x++) {}
Calculate the Fibonacci number for the current index x by calling the fibonacci function.
let fibResult = fibonacci(x) fibResult
Print the result fibResult to the console.
console.log(fibResult)
Store the last calculated Fibonacci number.
nthTerm = fibResult
Call the function with ↴
fibonacci(nTerms);
Generate the first 7 terms of the Fibonacci sequence ↴
function fib(nTerms)
nTerms = 7
for (let x = 0; x < nTerms; x++) {}
Calculate the Fibonacci number for the current index x by calling the fibonacci function.
fibonacci(x)
The current Fibonacci number is computed by adding the two previous numbers.
return fib(nTerms - 1) + fib(nTerms - 2)
x Iteration ↴
0 fib(0) fib(-1) + fib(-2) 0 Base case
1 fib(1) fib(0) + fib(-1) 1 Base case
2 fib(2) fib(1) + fib(0) 1
3 fib(3) fib(2) + fib(1) 2
4 fib(4) fib(3) + fib(2) 3
5 fib(5) fib(4) + fib(3) 5
6 fib(6) fib(5) + fib(4) 8
The function stacks calls, until it reaches the base case, then unwinds the stack to produce the result ↴
0, 1, 1, 2, 3, 5, 8
Generate the first 7 terms of the Fibonacci sequence.
const nTerms = 7;
function fibonacci(nTerms) {
if (nTerms < 2) {
return nTerms;
} else {
return fibonacci(nTerms - 1) + fibonacci(nTerms - 2);
}
} end of function
console.log("Fibonacci Sequence:");
let nthTerm;
for (let x = 0; x < nTerms; x++) {
let fibResult = fibonacci(x);
console.log(fibResult);
nthTerm = fibResult;
}
returns ↴
Fibonacci Sequence:
0
1
1
2
3
5
8 → printed to console