node-source-walk
v7.0.0
Published
Execute a callback on every node of a source code's AST and stop walking when you see fit
Downloads
6,653,298
Readme
node-source-walk
Synchronously execute a callback on every node of a file's AST and stop walking whenever you see fit.
npm install node-source-walk
Usage
const Walker = require('node-source-walk');
const walker = new Walker();
// Assume src is the string contents of myfile.js
// or the AST of an outside parse of myfile.js
walker.walk(src, node => {
if (node.type === whateverImLookingFor) {
// No need to keep traversing since we found what we wanted
walker.stopWalking();
}
});
By default, Walker will use @babel/parser
(supporting ES6, JSX, Flow, and all other available @babel/parser
plugins) and the sourceType: module
, but you can change any of the defaults as follows:
const walker = new Walker({
sourceType: 'script',
// If you don't like experimental plugins
plugins: [
'jsx',
'flow'
]
});
- The supplied options are passed through to the parser, so you can configure it according to
@babel/parser
's documentation.
Swap out the parser
If you want to supply your own parser, you can do:
const walker = new Walker({
parser: mySweetParser
});
- The custom parser must have a
.parse
method that takes in a string and returns an object/AST. - All of the other options supplied to the Walker constructor will be passed along as parser options to your chosen parser.
API
walk(src, callback)
- Recursively walks the given
src
from top to bottom src
: the contents of a file or its (already parsed) ASTcallback
: a function that is called for every visited node- The argument passed to
callback
will be the currently visited node.
- The argument passed to
moonwalk(node, callback)
- Recursively walks up an AST starting from the given node. This is a traversal that's in the opposite direction of
walk
andtraverse
node
: a valid AST nodecallback
: a function that is called for every node (specifically via visiting the parent(s) of every node recursively)- The argument passed to
callback
will be the currently visited node.
- The argument passed to
stopWalking()
- Halts further walking of the AST until another manual call of
walk
ormoonwalk
- This is super-beneficial when dealing with large source files (or ASTs)
traverse(node, callback)
- Allows you to traverse an AST node and execute a callback on it
- Callback should expect the first argument to be an AST node, similar to
walk
's callback
parse(src)
- Uses the options supplied to Walker to parse the given source code string and return its AST using the configured parser (or
@babel/parser
by default).