Is there any way for jscs to ignore rules per file, block or line?

This is available since jscs 1.6.0

For a file scope:

Put this on top of the file to ignore all rules

// jscs:disable

Put this on top of the file to ignore a specific rule:

// jscs:disable specificRule

Also for ignoring the whole file you can add it to .jscsrc, adding an entry to excludeFiles.

For block scope:

To ignore all rules

// Code here will be linted with JSCS.
// jscs:disable
// Code here will be ignored by JSCS.
// jscs:enable

To ignore a specific rule:

// Code here will be linted with JSCS.
// jscs:disable specificRule
// Code here will be ignored by JSCS.
// jscs:enable specificRule