Crash when using x[Symbol.toStringTag] = ...

[lcodes]

Hello,

I get a crash when using the following:

immutable.Map.prototype[Symbol.toStringTag] = function _toStringTag() {
  return 'Map';
};

However, this works fine:

let toStringTag = Symbol.toStringTag;
immutable.Map.prototype[toStringTag] = function _toStringTag() {
  return 'Map';
};

I just tried with the d0e0934 version of esdoc and it still crashes, here is the stack trace:

/mnt/data/Projects/esdoc/src/Publisher/Builder/DocResolver.js:121
          if (autoPrivate && this.name.charAt(0) === '_') {
                                      ^

TypeError: Cannot read property 'charAt' of undefined
    at Object.<anonymous> (/mnt/data/Projects/esdoc/src/Publisher/Builder/DocResolver.js:68:37)
    at /mnt/data/Projects/esdoc/node_modules/taffydb/taffy.js:743:17
    at each (/mnt/data/Projects/esdoc/node_modules/taffydb/taffy.js:126:17)
    at Object.<anonymous> (/mnt/data/Projects/esdoc/node_modules/taffydb/taffy.js:740:7)
    at Object.API.(anonymous function) [as update] (/mnt/data/Projects/esdoc/node_modules/taffydb/taffy.js:166:18)
    at DocResolver._resolveAccess (/mnt/data/Projects/esdoc/src/Publisher/Builder/DocResolver.js:66:18)
    at DocResolver.resolve (/mnt/data/Projects/esdoc/src/Publisher/Builder/DocResolver.js:24:10)
    at CoverageBuilder.DocBuilder (/mnt/data/Projects/esdoc/src/Publisher/Builder/DocBuilder.js:21:27)
    at new CoverageBuilder (/mnt/data/Projects/esdoc/src/Publisher/Builder/CoverageBuilder.js:7:37)
    at publish (/mnt/data/Projects/esdoc/src/Publisher/publish.js:79:5)
child_process.js:529
    throw err;
    ^

[paulirish]

Aye, we hit this today as well. @JoelEinbinder

[typhonrt]

Hi folks... So the reason for ESDoc failing here is that it is only assuming Identifier AST nodes. to determine the name. When doing the following this makes toStringTag an Identifier node:

let toStringTag = Symbol.toStringTag;
immutable.Map.prototype[toStringTag] = function _toStringTag() {
  return 'Map';
};

I have a separate fork of ESDoc that supports Babylon as the parser and I have made a patch that fixes this problem, but I want to get your guys feedback before submitting a PR to ESDoc.

I also added support for MyClass.prototype['ABC'] = ... or accepting a Literal / StringLiteral AST node to define the name.

It should be noted that currently ESDoc (or my fork) doesn't parse adding methods to the prototype of a class. IE MyClass.prototype.newMethod = () => { } is not added as a method in the class docs, but ends up as an unexported function doc. So you'll see it if you set "unexportIdentifier": true in your ESDoc configuration file, but it comes up as a function separate of the class.

I'd like to receive some comments on this as a potential enhancement such that when adding methods to a class prototype should they be picked up in the class documentation as a class method. It requires a bit more effort to support this with ESDoc, but should be possible.

For now though could you guys take a look and give a quick test with:
https://github.com/typhonjs-node-esdoc/esdoc

It's not published on NPM so you have to include it directly from GitHub ala:

devDependencies: {
  "esdoc": "git+https://git@github.com/typhonjs-node-esdoc/esdoc.git"
}

---

A secondary option if you have full control of the source code and want to see toStringTag to show up in the class method docs is this:

export default class MyClass
{
  /**
   * Defines toStringTag. 
   * @returns {string}
   */
   [Symbol.toStringTag]() { return 'MyClass'; }
}

[h13i32maru]

@ddude Thanks for report this bug. I fixed it on current master. I will publish new version at shortly.
Thanks.

[typhonrt]

You might also handle the literal case:

      if (this._node.id.type === 'MemberExpression') {
        this._value.name = ASTUtil.flattenMemberExpression(this._node.id);
      } 
      else if (this._node.id.type === 'Literal') {
        this._value.name = this._node.id.value;
      } else {
        this._value.name = this._node.id.name;
      }

Without supporting the Literal ESTree AST Node here this will crash: MyClass.properties['something'] = function() { ... } will crash just like MemberExpression did previously.

[h13i32maru]

I fixed this issue in e59820a
And I will release in next version