get-or-else

get-or-else

Simple Get Or Else module written in JavaScript ES5.

Request an object property at a given namespace with a backup value, incase the desired namespace does not yield a result.

Useful if you have an untrustworthy data source. It will probably save you a bit of if, else-ery.

Example ES5

var getOrElse = require("get-or-else");

window.a = {x:4};
getOrElse({ get: [window,'a.b.c'], else: {} });
// {} - does not exist, so `else` is used
getOrElse({ get: [window,'a'], else: {} })
// {x:4} - does exist, so expected value is returned

Example ES6 Redux

import getOrElse from 'get-or-else';

export const name = (state = {}, action = {}) => {

  switch(action.type) {

  case 'SET_NAME':
    return {
      ...state,
      ...getOrElse({ get: [action,'payload.name'], else: {} });
    };

  default:
    return state;

  }
};

Example ES6 React

see this repo get-or-else-demo

import React from 'react';
import ReactDOM from 'react-dom';
import getOrElse from 'get-or-else';

const nameObj = {
  salutation: 'Mr',
  name: {
    first: 'James'
  }
};

const salutation = getOrElse({  get: [nameObj,'salutation'], else: false });

const NameComponent = () => {
  return (
    <h1>
      We have been expecting you

      {salutation && <span> {salutation} </span>}

      <span> {getOrElse({ get: [nameObj,'name.first'], else: '' })}</span>

      <span> {getOrElse({ get: [nameObj,'name.last'], else: '' })}</span>
    </h1>
  );
};

ReactDOM.render(<NameComponent />, document.getElementById('root'));

/* NameComponent Renders `
<h1>
  We have been expecting you
  <span> Mr </span>
  <span>James</span>
  <span></span>
</h1>`

nameObj.name.last does not exist so it does not display
*/

NPM Package

get-or-else

Browser compatibility

IE 9 or greater - Array.every on Mozilla's compatibility chart

The getOrElse Module

/**
 * @param {Object} getOrElseObj
 * @param {Array} getOrElseObj.get
 * @param {Object} getOrElseObj.get[0] - the root object to your namespace.
 * e.g. this, window, someObj (Must exist).
 * @param {String} getOrElseObj.get[1] - a string representation of the namespace you
 * are targeting to get it's property. e.g. 'a.b.c.d'
 * @returns {Object} the item you hope for `get`, or a backup item `else` if it does not exist.
 * @example
 * GIVEN
 * window.a = {x:4}
 *
 * getOrElse({ get: [window,'a.b.c'], else: {} }) // {} - does not exist, so `else` is used
 * getOrElse({ get: [window,'a'], else: {} }) // {x:4} - does exist, so expected value is returned
 */

var getOrElse = function( getOrElseObj ) {
  if (!getOrElseObj.get[0]) return getOrElseObj.else;
  var contextObj = getOrElseObj.get[0];
  var namespace = getOrElseObj.get[1].split('.');
  var value = contextObj; // reassigns to obj[key] on each array.every iteration
  return (
    namespace.every( function( key ) {
      return (value = value[key]) != undefined
    })
  ) ? value : getOrElseObj.else;
};

module.exports = getOrElse;

Run the tests

Given you have Node installed, cd into this folder and:

npm install
npm test