# Number Pattern Programs In JavaScript

### Number Pattern

A number pattern is a series of numbers (integers) that creates a certain pattern or geometrical shape like square, pyramid, triangle, etc by arranging itself in a certain order. These orders are defined by programs that you have to generate as a programming skill.

You have already seen star pattern and alphabet pattern programs similar logic is applied here with numbers. These pattern programs will boost your programming skills mainly creates a good command over loops.

## Program To Print Number Pattern In JavaScript

Here we have discussed 10 different number patterns with their programs in detail.

## 1. Triangle pattern (1)

1 1 2 1 2 3 1 2 3 4 1 2 3 4 5

The pattern shown above is a triangle-shaped pattern using numbers. To create the above pattern run 2 nested loops, internal loop will take care of rows (number of iterations and printing pattern) while the external loop will look for a column mechanism.

Run external loop for 'n' number of times from 1 to 'n', where 'n' is height of triangle, i.e `for(let i = 0;i <= n; i++)`

.

The internal loop will run for 1 time in the first iteration of external code, 2 times in the second iteration, and so on and will add the iteration number of the internal loop to the string.

```
let n = 5; // height of pattern
let string = "";
// External loop
for (let i = 1; i <= n; i++) {
// Internal loop
for (let j = 1; j <= i; j++) {
string += j;
}
string += "\n";
}
console.log(string);
```

## 2. Triangle pattern (2)

1 2 2 3 3 3 4 4 4 4 5 5 5 5 5

This pattern is similar to the previous pattern, the only difference is in characters. You can see in this pattern characters are the same within a row and only changing in the next iteration of the external loop. So you can simply use 'i' while creating characters instead of 'j' because the value of i stays the same within a row.

```
let n = 5; // height of pattern
let string = "";
// External loop
for (let i = 1; i <= n; i++) {
// Internal loop
for (let j = 1; j <= i; j++) {
string += i;
}
string += "\n";
}
console.log(string);
```

## 3. Triangle pattern (3)

1 2 3 4 5 6 7 8 9 10

The shape of this pattern is the same as the previous one only difference is in the printed number. The number is increasing in each and every iteration. To achieve this you can simply create a random variable ('count' in the below example) and increase it in every iteration.

```
let n = 4; // height of pattern
let string = "";
let count = 1;
// External loop
for (let i = 1; i <= n; i++) {
// Internal loop
for (let j = 1; j <= i; j++) {
string += count;
count++;
}
string += "\n";
}
console.log(string);
```

## 4. Reverse triangle (1)

12345 1234 123 12 1

In this pattern control, internal loop such as it runs for 'n' times in the 1st iteration of the external loop, 'n - 1' times in the 2nd iteration, and so on. To get this set initialization variable `j`

less than `'n - i + 1'`

. Now use the initialization variable of the internal loop for character increment.

```
let n = 5; // height of pattern
let string = "";
// External loop
for (let i = 1; i <= n; i++) {
for (let j = 1; j <= n - i + 1; j++) {
string += j;
}
string += "\n";
}
console.log(string);
```

## 5. Reverse triangle (2)

54321 5432 543 54 5

This pattern is the same as the previous pattern only difference is that instead of starting the number from 1 it is starting from 'n', where 'n' is the height of the pattern.

To achieve this use `'n - j + 1'`

for number creation.

```
let n = 5; // height of pattern
let string = "";
// External loop
for (let i = 1; i <= n; i++) {
for (let j = 1; j <= n - i + 1; j++) {
string += n - j + 1;
}
string += "\n";
}
console.log(string);
```

## Pattern 6:

54321 4321 321 21 1

This pattern is the same as the previous pattern only difference is the last pattern starts from number 1 but this pattern ends with number 1 in each row.

To achieve this use `'n - i - j + 2'`

for printing number as it will end each row with 1.

```
let n = 5; // height of pattern
let string = "";
// External loop
for (let i = 1; i <= n; i++) {
for (let j = 1; j <= n - i + 1; j++) {
string += n - j - i + 2;
}
string += "\n";
}
console.log(string);
```

## 7. Number pyramid pattern (1)

1 123 12345 1234567 123456789

This is a pyramid-shaped pattern using the numbers, we have already created the pyramid pattern using stars. Using the same technique create the pattern and instead of printing stars, print numbers starting from 1 in each row.

This program will contain 2 internal loops, 1st internal loop will print the spaces and 2nd internal loop will print numbers starting from 1 and `2 * i -1`

times in each row.

```
let n = 5;
let string = "";
// External loop
for (let i = 1; i <= n; i++) {
// creating spaces
for (let j = 1; j <= n - i; j++) {
string += " ";
}
// creating numbers
for (let k = 1; k <= 2 * i - 1; k++) {
string += k;
}
string += "\n";
}
console.log(string);
```

## 8. Number Pyramid Pattern (2)

1 234 56789

This pattern is the same as the previous pattern only difference is that the number increases in this pattern in each and every iteration, while in the last pattern it starts with 1 again from each row.

To keep track of this create a variable (called count here) and increase it in every iteration of the internal loop and use this variable as a number for printing.

```
let n = 3;
let count = 1;
let string = "";
// External loop
for (let i = 1; i <= n; i++) {
// creating spaces
for (let j = 1; j <= n - i; j++) {
string += " ";
}
// creating numbers
for (let k = 1; k <= 2 * i - 1; k++) {
string += count;
count++;
}
string += "\n";
}
console.log(string);
```

## 9. Reverse Pyramid Pattern

123456789 1234567 12345 123 1

This is a reverse pyramid pattern using numbers. To create this control the formation of spaces and creation of numbers in reverse order. See the code below to understand.

Compare codes of pyramid pattern and reverse pyramid pattern for better understanding.

```
let n = 5;
let string = "";
// External loop
for (let i = 1; i <= n; i++) {
// creating spaces
for (let j = 1; j < i; j++) {
string += " ";
}
// creating numbers
for (let k = 1; k <= 2 * (n - i + 1) - 1; k++) {
string += k;
}
string += "\n";
}
console.log(string);
```

## 10. Number Diamond Pattern

1 123 12345 1234567 123456789 1234567 12345 123 1

The diamond pattern is a combination of the pyramid and the reverse pyramid number patterns.

```
let n = 5;
let string = "";
// Pyramid
for (let i = 1; i <= n; i++) {
for (let j = 1; j < n - i + 1; j++) {
string += " ";
}
for (let k = 1; k <= 2 * i - 1; k++) {
string += k;
}
string += "\n";
}
// Reverse Pyramid
for (let i = 1; i <= n - 1; i++) {
for (let j = 1; j < i + 1; j++) {
string += " ";
}
for (let k = 1; k <= 2 * (n - i) - 1; k++) {
string += k;
}
string += "\n";
}
console.log(string);
```

## Pattern 11: Hourglass Pattern

123456789 1234567 12345 123 1 123 12345 1234567 123456789

Hourglass pattern is a combination of the reverse pyramid and pyramid number patterns.

```
let n = 5;
let string = "";
// Reverse Pyramid
for (let i = 1; i <= n; i++) {
for (let j = 1; j < i; j++) {
string += " ";
}
for (let k = 1; k <= 2 * (n - i + 1) - 1; k++) {
string += k;
}
string += "\n";
}
// Pyramid
for (let i = 1; i <= n - 1; i++) {
for (let j = 1; j < n - i; j++) {
string += " ";
}
for (let k = 1; k <= 2 * (i + 1) - 1; k++) {
string += k;
}
string += "\n";
}
console.log(string);
```

## 12. Number Pascal Pattern

1 12 123 1234 12345 1234 123 12 1

Pascal pattern is a combination of triangle and reverse triangle pattern using numbers.

```
let n = 5;
let string = "";
// Pyramid
for (let i = 1; i <= n; i++) {
for (let k = 1; k <= i; k++) {
string += k;
}
string += "\n";
}
// Reverse Pyramid
for (let i = 1; i <= n - 1; i++) {
for (let k = 1; k <= n - i; k++) {
string += k;
}
string += "\n";
}
console.log(string);
```

### Conclusion

In this article, you learned and created 12 different number patterns in javascript. You can think of number pattern programs as 1 step above star pattern programs because they need little more logic than start pattern programs. Visit other pattern programs from the links below.

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