safe-read v1.1.2

safe-read

Allows you to extract a specific property in a deep nested object without having to check the existance of each property in-between.

Install

npm install safe-read --save

Example

var itemObj = {
    test: [
        {
            foo: {
                bar: [
                    ['a', 3]
                ]
            }
        }
    ]
};

var errorObj = {
    test: [
        {
            error: [
                {
                    code: 400,
                    message: 'Foobar!'
                }
            ]
        }
    ]
};

console.log(safeRead(itemObj, 'test.0.foo.bar.0.0'));       // 'a'
console.log(safeRead(errorObj, 'test.0.foo.bar.0.0'));      // undefined
console.log(safeRead(errorObj, 'test.0.error.0.message'));  // 'Foobar!'

Debugging

Debugging is done via the debug package and the DEBUG environmental variable.

Use cases

Can be used when extracting data from a complex API response like the ones from Amazon’s Product Advertising API:

var response = [
  {
    ...
    "ItemAttributes":[
      {
        ...
        "UPCList":[
          {
            "UPCListElement":[
              "027242877115",
              "799959956994",
              "780746812258"
            ]
          }
        ],
        ...
      }
    ]
  }
];

Normally, to get the first UPCListElement, you would have to do something like:

if (
    response &&
    response[0] &&
    response[0].ItemAttributes &&
    response[0].ItemAttributes[0] &&
    response[0].ItemAttributes[0].UPCList &&
    response[0].ItemAttributes[0].UPCList[0] &&
    response[0].ItemAttributes[0].UPCList[0].UPCListElement &&
    response[0].ItemAttributes[0].UPCList[0].UPCListElement[0]
) {
    listElement = response[0].ItemAttributes[0].UPCList[0].UPCListElement[0];
}

With safe-read, you can do just:

listElement = safeRead(response, '0.ItemAttributes.0.UPCList.0.UPCListElement.0');

If response is not an object or if any of the intermediate properties do not exist, undefined is returned.