> For the complete documentation index, see [llms.txt](https://gofast.disasm.dev/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gofast.disasm.dev/basics/parsing-javascript-files.md).

# Parsing JavaScript Files

## Parsing JavaScript Files

The **parser** module in `go-fAST` allows you to turn JavaScript source code into a rich, structured Abstract Syntax Tree (AST). This is the foundation for any static analysis, transformation, or introspection you want to perform.

***

### ✨ Basic Usage

To parse a JavaScript string into an AST, use the `parser.ParseFile()` function:

```go
prog, err := parser.ParseFile(src)
if err != nil {
    panic("error parsing src script")
}
```

If successful, `prog` will contain an `*ast.Program` node — the root of your AST.

***

### 📂 Example: Parsing a File

```go
package main

import (
	"fmt"
	"os"

	"github.com/t14raptor/go-fast/parser"
)

func main() {
	data, err := os.ReadFile("in.js")
	if err != nil {
		fmt.Println("Failed to read file:", err)
		return
	}

	ast, err := parser.ParseFile(string(data))
	if err != nil {
		fmt.Println("Parsing failed:", err)
		return
	}

	fmt.Println("Successfully parsed AST root:", ast.Type())
	// You can now traverse or transform the AST
}
```

***

### 📦 What You Get

The result of `parser.ParseFile()` is an `*ast.Program`, which contains a `Body` field consisting of a list of statements. This structure mirrors ECMAScript’s source grammar:

```go
type Program struct {
	Body ast.Statements // List of top-level statements
}
```

Each node in the tree implements the `VisitableNode` interface, allowing you to use the Visitor API for traversal and analysis.


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