A simple helper function for getting deeply nested object property

code.js

const getObjectProperty = (obj, path, defaultValue="", returnUndefined=true) => {
  const checkForDefaultValue = value =>
    value !== undefined ? value : undefined;

  if (path === undefined) {
    return obj;
  }
  try {
    const value = path.split('.').reduce((o, i) => o[i], obj);
    if (value === undefined && returnUndefined) return value;
    return value !== undefined ? value : checkForDefaultValue(defaultValue);
  } catch (e) {
    if (e instanceof TypeError) return checkForDefaultValue(defaultValue);
    throw e;
  }
};


/*
 const a = {
  b: {
    c: [
      {
        d: {
          e: 14
        }
      },
      [16, 11]
    ],
    d: 12
  }
};

getObjectProperty(a, 'b.d',  "Default!");
// 12

getObjectProperty(a, 'b.e', "Not a property");
// undefined

getObjectProperty(a, 'b.e', "Not a property", false);
// Not a property


getObjectProperty(a, 'b.c.0.d.e', "Not a property!");
// 14

getObjectProperty(a, 'b.c.1.0', "Not a property!");
//16
*/

@ahkohd

getObjectProperty(testObject, 'd', 'Not Found');

I feel this should actually return undefined, because testObject.d is actually having a value of undefined

My initial idea was that this

return path.split(".").reduce((o, i) => o[i], obj);

returns an undefined except when we are trying to read from undefined like undefined.name that is when the catch block gets invoked and a defaultValue can be used.

Very well, for my use case the later function works. Maybe you should provide a flag.

Very well, for my use case the later function works. Maybe you should provide a flag.

@ahkohd okay, I added a flag to allow undefined returns or fall back to a set default value, I also included your example. 👌🏾

Great!