The JS manual shows tag-name arrays created with new Array() or array literals. Call ReadFromTag(tagNames) to read the values and iterate over the returned array. Batch writes use WriteToTag(tagNames, values) with corresponding entries in the two arrays.
It also includes JSON.parse, JSON.stringify, a custom find_json function that searches objects by key/value, and a Math.round example. Start with these documented patterns and validate the actual project. The examples do not certify a complete JavaScript standard version, every math-library function or performance at arbitrary scale.