tern provides a support for ES5 with ecma5.json. It uses acorn parser which is able to parse ES5 JavaScript code.

After installing and converting your project as Tern Project, go at Tern project property, click on Tern item and select the ECMAScript 5 version:

Array

ECMAScript 5 gives the capability to provide completion for Array :

In this sample, arr is an Array of number, the completion for elt item provides Number methods :