Rewrite actually modify the source object

The rewriters actually modify the source meta object:

    winston.rewriters.push(function(level, msg, meta) {
      const actionType = meta && meta.data && meta.data.action;
      const valueToHide = meta && meta.data && meta.data.text;
      if (actionType === 'typeText' && valueToHide) {
        console.log('Logs filtering:', actionType, valueToHide)
        meta.data.text = null;
      }

      return meta;
    })

It should be cloned before being passed to the rewriter function.

[netoneko]

And this is detrimental to actual apps. Simple call to winston.log('Hello', myBusinessObject) will modify the business object. There should at least be a warning about this behavior.

This is a major issue of data integrity compromised by calling a log function.

[indexzero]

@lasryaric this is by design. @jcready is correct when he says:

“A deep clone would be detrimental to performance and a shallow clone would not prevent mutation of deeply nested objects. It seems like you would be better off just cloning the meta object yourself if you’re going to be mutating it.”

As to your comment about “winston is a fancy console.log” @netoneko, I would point out that console.log does not have rewrite functionality built into it.