pxt-core/common-docs/blocks.md

Microsoft MakeCode provides Blocks / JavaScript / Python tools and editors

# Blocks language

### @description Language constructs for the Block editor.

## #blocksbase

Blocks snap into each other to define the program that will run.
Blocks can be event (buttons, shake, ...) or need to be snapped into an event to run.
The [on-start](/blocks/on-start) event runs first.

## Blocks

```namespaces
for (let i = 0;i<5;++i) {}
if (true){}
let x = 0;
```

## Built-in objects #builtins

```namespaces
Math.randomRange(0,5);
"".compare("");
[0].push(0);
```

## See Also

[logic](/blocks/logic), [loops](/blocks/loops), [variables](/blocks/variables),
[math](/reference/math), [text](/reference/text), [arrays](/reference/arrays)

[on-start](/blocks/on-start), [javascript blocks](/blocks/javascript-blocks), [custom blocks](/blocks/custom)