pxt-calliope/docs/js/sequence.md
2016-11-01 17:44:37 -07:00

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# Sequencing
By calling one function after another, in sequence, you can create an animation:
```typescript
basic.showLeds(`
. # . # .
. . . . .
. . # . .
# . . . #
. # # # .
`);
basic.showLeds(`
. # . # .
. . . . .
. . . . .
. # # # .
# . . . #
`);
```
### The semicolon
In JavaScript, the semicolon (;) is used to terminate (or end) a statement. However, in most
cases, the semicolon is optional and can be omitted. So both code sequences below are
legal:
```typescript
basic.showNumber(1)
basic.showNumber(2)
```
```typescript
basic.showNumber(1);
basic.showNumber(2);
```
### The empty statement
In JavaScript, there is the concept of an *empty statement*, which is whitespace followed by
a semicolon in the context where a statement is expected.
So, the following code is an infinite loop
followed by a call to `showNumber` that will never execute:
```typescript-ignore
while(true) ;
basic.showNumber(1);
```
### ~hint
For the @boardname@, we don't allow a program to contain an empty statement, such as shown above.
If you really want an empty statement, you need to use curly braces to delimit an empty statement block:
```typescript
while(true) { }
basic.showNumber(1);
```
### ~
[Read more](http://inimino.org/~inimino/blog/javascript_semicolons) about semicolons in JavaScript.
### ~button /js/variables
NEXT: Variable Declarations
### ~