packages/babel-helper-hoist-variables/src/index.js
import * as t from "@babel/types";
const visitor = {
Scope(path, state) {
if (state.kind === "let") path.skip();
},
Function(path) {
path.skip();
},
VariableDeclaration(path, state) {
if (state.kind && path.node.kind !== state.kind) return;
const nodes = [];
const declarations: Array<Object> = path.get("declarations");
let firstId;
for (const declar of declarations) {
firstId = declar.node.id;
if (declar.node.init) {
nodes.push(
t.expressionStatement(
t.assignmentExpression("=", declar.node.id, declar.node.init),
),
);
}
for (const name of Object.keys(declar.getBindingIdentifiers())) {
state.emit(t.identifier(name), name, declar.node.init !== null);
}
}
// for (var i in test)
if (path.parentPath.isFor({ left: path.node })) {
path.replaceWith(firstId);
} else {
path.replaceWithMultiple(nodes);
}
},
};
export default function (path, emit: Function, kind: "var" | "let" = "var") {
path.traverse(visitor, { kind, emit });
}