eval-json-path's Introduction

eval-json-path

Evaluate/Query the value of json object at given path

Commonly js object variable can be accessed by property name or index. This module allow to access by path/steps given by a string

Usage

const evalJsonPath = require('eval-json-path')

const value = evalJsonPath(obj, 'prop.subprop[prett-prop][3].lastprop')

const sameValue = obj.prop.subprop['prett-prop'][3].lastprop

The evaluation is done by each step, which is null-safe, any not-existing step will result undefined or fallback

API

evalJsonPath(obj, path, fallback)

obj: The object should has sub property
path: A string represent the path/steps
fallback: A optional fallback for any not-existing step

More Examples

const obj = {
  step1: {
    step2: {
      'pretty.nice-step': [
        {},
        {step3: 4}
      ]
    }
  }
}

evalJsonPath(null, 'step1'); // undefined

evalJsonPath(undefined, 'step1'); // undefined

evalJsonPath(3, 'step1'); // undefined

evalJsonPath(false, 'step1'); // undefined

evalJsonPath(obj, 'step1'); // same as obj.step1

evalJsonPath(obj, 'step1.step2'); // same as obj.step1.step2

evalJsonPath(obj, 'step1.step2[pretty.nice-step]'); // obj.step1.step2['pretty.nice-step'])

evalJsonPath(obj, 'step1.step2[pretty.nice-step][1].step3'); // obj.step1.step2['pretty.nice-step'][1].step3)

evalJsonPath(obj, 'step1.xxxxx[pretty.nice-step][1].step3'); // any non-exist step result undefined

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