HED in JavaScript

The JavaScript code for HED validation is in the validation directory of the hed-javascript repository located at https://github.com/hed-standard/hed-javascript.

Javascript tool installation

You can install the validator using npm:

npm install hed-validator

Javascript package organization

This package contains two sub-packages.

hedValidator.validator validates HED strings and contains the functions:

buildSchema imports a HED schema and returns a JavaScript Promise object.
validateHedString validates a single HED string using the returned schema object.

hedValidator.converter converts HED strings between short and long forms and contains the following functions:

buildSchema behaves similarly to the buildSchema function in hedValidator.validator except that it does not work with attributes.

convertHedStringToShort converts HED strings from long form to short form.

convertHedStringToLong converts HED strings from short form to long form.

Javascript programmatic interface

The programmatic interface to the HED JavaScript buildSchema must be modified to accommodate a base HED schema and arbitrary library schemas. The BIDS validator will require additional changes to locate the relevant HED schemas from the specification given by "HEDVersion" in dataset_description.json.

The programmatic interface is similar to the JSON specification of the proposed BIDS implementation except that the "fileName" key has been replaced by a "path" key to emphasize that callers must replace filenames with full paths before calling buildSchema.

Example: JSON passed to buildSchema.

    "path": "/data/wonderful/code/mylocal.xml",
    "libraries": {
        "la": {
            "libraryName": "libraryA",
            "version": "1.0.2"
        "lb": {
            "libraryName": "libraryB",
            "path": "/data/wonderful/code/HED_libraryB_0.5.3.xml"

NOTE: This interface is proposed and is awaiting resolution of BIDS PR #820 on file passing to BIDS.