Transforming $.now

1 step: find a CallExpression node

Visitor:

visitor: {
  CallExpression(path) {
    // …
  }
}

2 step: ensure that the CallExpression is $.now

Input:

/*
  $.now();
  ^ ^^^
*/

Visitor:

const { callee, arguments: args } = path.node;

if (!t.isMemberExpression(callee)) {
  return;
}

if (
  callee.object.name === "$" &&
  callee.property.name === "now"
) {
  // yes …
}

3 step: transforming $.now into Date.now

For simplicity we can directly mutate the callee object.

Diff:

-$.now();
+Date.now();

Visitor:

// Rename $.now to Date.now
callee.object = t.identifier("Date");