streaming command line newline-delimited json transformer utility

you must pipe newline-delimited JSON data in (one JSON stringified object per line). you will receive the same format out

$ npm install jsonmap -g

this will be each line of JSON that gets parsed out of the incoming newline-delimited json stream. you can also use _ as a shorthand for this, and you are allowed to require things.

there are two 'modes', the first is where you modify this:

$ echo'{"foo": "bar"}\n{"baz": "taco"}'| jsonmap "this.pizza = 1"{"foo":"bar","pizza":1}{"baz":"taco","pizza":1}

the second mode is where you return a new object:

$ echo'{"foo": "bar", "cat": "yes"}\n{"baz": "taco", "cat": "yes"}'| jsonmap "{cat: this.cat}"{"cat":"yes"}{"cat":"yes"}

if your code gets too complex and you'd rather use an external file you can also just specify a module to get required:

$ echo'{"foo": "bar"}\n{"baz": "taco"}'| jsonmap --file=transform.js{"foo":"bar","pizza":1}{"baz":"taco","pizza":1}

the above will work if transform.js has the following contents:

module.exports=function(){this.pizza=1}

if you have es6 template strings enabled on your platform (e.g. iojs), template strings will work as well

$ echo'{"meal": "pizza"}\n{"meal": "taco"}'| jsonmap '`i love ${this.meal}`'"i love pizza""i love taco"

if you want to provide a through2 function in a file for more control, or async, you can

$ echo'{"foo": "bar"}\n{"baz": "taco"}'| jsonmap --file=transform.js --through{"foo":"bar","pizza":1}{"baz":"taco","pizza":1}

the above will work if transform.js has the following contents:

module.exports=function(obj,enc,next){varself=this;if(obj.foo==='bar')returnnext()// skip the barprocess.nextTick(function(){self.push({count: obj.pizza})next()})}

you disable JSON parsing (to e.g. process a file line by line as JS strings) by passing jsonmap --no-parse