replace(): replace with 2 nodes?

[rstacruz]

Would it be possible to replace a node with multiple statements? I understand this can't work on all places (only in bodys), but it'd be useful for some cases.

estraverse.replace(tree, {
  enter: function (node, parent) {
    if (/* something */) {
      return [
        { type: 'FunctionDeclaration', body: /* ... */ },
        { type: 'FunctionDeclaration', body: /* ... */ } ];
    }
  }
});

An example use case would be to to change a ForStatement (for (x;y;z){a}) into a WhileStatement (x; while (y) { z; a; }), which will be useful for js2coffee.

[goatslacker]

Came here to ask the same question. If it is possible it's undocumented.

[Constellation]

Ah, currently, estraverse doesn't support it.

[exander77]

I second this feature.

[trusktr]

Just came looking for this too. A workaround is to run logic on the parent, replace the target child with the two children on the parent, then return the parent when you've traversed to that parent.

[WelaurS]

Temporary fix:

return {
    type: esprima.Syntax.Program,
    body: bodyStatementsArray,
}

Will do pull request later

[sanex3339]

+1

[lwyj123]

+1

[rootgrandfather]

+1

[ptrcnull]

Dirty workaround that should work with BlockStatement:

estraverse.replace(tree, {
  enter: (node, parent) => {
    const nodes = // ...
    const index = parent.body.findIndex(n => n === node)
    parent.body.splice(index, 1, ...nodes)
  }
})

Using this instead of WelaurS' fix, because inserting a Program node inside a BlockStatement can mess up escodegen's formatting.

[wlbksy]

Can we make ptrcnull's implementation into codebase ?