From basic to advanced: test how well you know JavaScript, refresh your knowledge a bit, or prepare for your coding interview! 💪 🚀
*****
*****
*****
*****
*****To create square star pattern run 2 nested for loop. Execute each loop for 'n' number of times, where 'n' is number of rows/columns in the square, i.e for(let i = 0;i < n;i++).
The internal loop will run for 'n' number of times which will print starts in a row and at the end of the loop print a newline (\n).
Answer
let n = 5;
let string = "";
for (let i = 1; i <= n; i++) {
for (let j = 0; j < n; j++) {
string += "*";
}
string += "\n";
}
console.log(string);*
**
***
****
*****To create the right triangle pattern in javascript again run 2 nested for loop external loop will take care of columns of pattern and the internal loop will print rows of the pattern.
You can observe from the above-shown pattern that we need to run an external loop for 'n' time while the internal loop runs for 1 time in the first execution, 2 times in the second execution, and so on till 'n' times.
You can use the value of i from the external loop which will increase from 1 to 'n' inside the internal loop as a condition.
Answer
let n = 5;
let string = "";
for (let i = 1; i <= n; i++) {
for (let j = 0; j < i; j++) {
string += "*";
}
string += "\n";
}
console.log(string); *
**
***
****
*****To create a left triangle pattern in javascript you will have to deal with 3 loops, 1 of which is external and 2 are internal. The external loop will execute internal loops for 'n' number of times and the internal loop will design a pattern for each row.
From the above pattern, you can see each row has a series of stars and spaces. The number of stars in a row starting from 1 preceding with 'n-1' spaces and ends with 'n' star and 0 spaces.
Create 2 internal loops, 1st print n - i spaces and 2nd print i stars, where i is the number of time external loop executed.
Answer
let n = 5;
let string = "";
for (let i = 1; i <= n; i++) {
for (let j = 0; j < n - i; j++) {
string += " ";
}
for (let k = 0; k < i; k++) {
string += "*";
}
string += "\n";
}
console.log(string);*****
****
***
**
*To create a downward triangle star pattern use a nested loop, it is also known as a reverse star pattern. From the above-shown pattern, you can see the number of stars decreases from 'n' to 1.
Run a for loop inside an external loop whose number of iterations decreases from 'n' to 1.
Answer
let n = 5;
let string = "";
for (let i = 0; i < n; i++) {
for (let k = 0; k < n - i; k++) {
string += "*";
}
string += "\n";
}
console.log(string); *
***
*****
*******
*********The Pyramid star pattern is a famous star pattern, you can see the shape of the pattern above.
It uses 2 loops inside the external loop one for printing spaces and the other to print stars.
The number of spaces in a row is n - i in each row and the number of stars in a row is 2 * i - 1.
Answer
let n = 5;
let string = "";
for (let i = 1; i <= n; i++) {
for (let j = 1; j <= n - i; j++) {
string += " ";
}
for (let k = 0; k < 2 * i - 1; k++) {
string += "*";
}
string += "\n";
}
console.log(string);*********
*******
*****
***
*The reversed pyramid star pattern is a pyramid pattern upside-down.
It uses 2 loops inside the external loop one for printing spaces and the other to print the star. First loop prints spaces and other loop print stars. Here is the code of the reverse pyramid star pattern.
The number of spaces in a row is i and the number of stars is 2 * (n - i) - 1.
Answer
let n = 5;
let string = "";
for (let i = 0; i < n; i++) {
for (let j = 0; j < i; j++) {
string += " ";
}
for (let k = 0; k < 2 * (n - i) - 1; k++) {
string += "*";
}
string += "\n";
}
console.log(string); *
***
*****
*******
*********
*******
*****
***
*The diamond star pattern is a combination of the pyramid and the reverse pyramid star pattern.
Observe in the above pattern it is a pyramid and a reverse pyramid together. Use the above concepts to create a diamond shape.
Answer
let n = 5;
let string = "";
for (let i = 1; i <= n; i++) {
for (let j = n; j > i; j--) {
string += " ";
}
for (let k = 0; k < i * 2 - 1; k++) {
string += "*";
}
string += "\n";
}
for (let i = 1; i <= n - 1; i++) {
for (let j = 0; j < i; j++) {
string += " ";
}
for (let k = (n - i) * 2 - 1; k > 0; k--) {
string += "*";
}
string += "\n";
}
console.log(string);*********
*******
*****
***
*
***
*****
*******
*********The hourglass star pattern is also made up of pyramid and reverse pyramid star pattern.
Observe in the above pattern it is a reverse pyramid and a pyramid together. Use the above concepts to create a diamond shape.
Answer
let n = 5;
let string = "";
for (let i = 0; i < n; i++) {
for (let j = 0; j < i; j++) {
string += " ";
}
for (let k = 0; k < (n - i) * 2 - 1; k++) {
string += "*";
}
string += "\n";
}
for (let i = 2; i <= n; i++) {
for (let j = n; j > i; j--) {
string += " ";
}
for (let k = 0; k < i * 2 - 1; k++) {
string += "*";
}
string += "\n";
}
console.log(string);*
**
***
****
*****
****
***
**
*The right pascal star pattern is created using 2 nested loops.
You can observe in the above pattern it is nothing but the right triangle star pattern and reversed triangle star pattern together. Here is the code for the right pascal star pattern.
Answer
let n = 5;
let string = "";
for (let i = 1; i <= n; i++) {
for (let j = 0; j < i; j++) {
string += "*";
}
string += "\n";
}
for (let i = 1; i <= n - 1; i++) {
for (let j = 0; j < n - i; j++) {
string += "*";
}
string += "\n";
}
console.log(string); *
**
***
****
*****
****
***
**
*The left pascal star pattern is also created using 2 nested loops.
It is the same as the right pascal star pattern just mirrored. Here is the code for the right pascal star pattern.
Answer
let n = 5;
let string = "";
for (let i = 1; i <= n; i++) {
for (let j = 0; j < n - i; j++) {
string += " ";
}
for (let k = 0; k < i; k++) {
string += "*";
}
string += "\n";
}
for (let i = 1; i <= n - 1; i++) {
for (let j = 0; j < i; j++) {
string += " ";
}
for (let k = 0; k < n - i; k++) {
string += "*";
}
string += "\n";
}
console.log(string);11. Testing your 'this' knowledge in JavaScript: What is the output of the following code?.(eg. company name)
var length = 10;
function fn() {
console.log(this.length);
}
var obj = {
length: 5,
method: function (fn) {
fn();
arguments[0]();
},
};
obj.method(fn, 1);Answer
10
2Why isn’t it 10 and 5?
In the first place, as fn is passed as a parameter to the function method, the scope (this) of the function fn is window. var length = 10; is declared at the window level. It also can be accessed as window.length or length or this.length (when this === window.)
method is bound to Object obj, and obj.method is called with parameters fn and 1. Though method is accepting only one parameter, while invoking it has passed two parameters; the first is a function callback and other is just a number.
When fn() is called inside method, which was passed the function as a parameter at the global level, this.length will have access to var length = 10 (declared globally) not length = 5 as defined in Object obj.
Now, we know that we can access any number of arguments in a JavaScript function using the arguments[] array.
Hence arguments[0]() is nothing but calling fn(). Inside fn now, the scope of this function becomes the arguments array, and logging the length of arguments[] will return 2.