What is the best way to filter this object using lodash or JavaScript?

Question

I am having an object like this

 var result = {
    case1: {
        documents: [{
            versionSeriesId: 'BkO9EXxL',
            documentTypeId: '80',
            isDeleted: false
        }],
        answer: true
    },
    case2: {
        documents: [{
            versionSeriesId: 'BkO9EXxL',
            documentTypeId: '80',
            isDeleted: false
        }],
        answer: true
    },
    case3: {
        documents: []
    },
    case4: {
        documents: [{
            versionSeriesId: 'BkO9EXxL',
            documentTypeId: '80',
            isDeleted: false
        }],
        answer: false
    }
}

I want to filter the object which is having the answer:true only. The result should be like this:

{
    case1: {
        documents: [{
            versionSeriesId: 'BkO9EXxL',
            documentTypeId: '80',
            isDeleted: false
        }],
        answer: true
    },
    case2: {
        documents: [{
            versionSeriesId: 'BkO9EXxL',
            documentTypeId: '80',
            isDeleted: false
        }],
        answer: true
    }
}

How can I do this?

Answer 1

You can do this quickly and without the need for an external library just by using Object.keys and then use the Array.forEach method to compile a new object.

var filtered = {};
Object.keys(result).forEach(function(item) {
  if (result[item].answer === true) {
    filtered[item] = result[item];
  }
});

Test with the snippet below:

 var result = { case1: { documents: [{ versionSeriesId: 'BkO9EXxL', documentTypeId: '80', isDeleted: false }], answer: true }, case2: { documents: [{ versionSeriesId: 'BkO9EXxL', documentTypeId: '80', isDeleted: false }], answer: true }, case3: { documents: [] }, case4: { documents: [{ versionSeriesId: 'BkO9EXxL', documentTypeId: '80', isDeleted: false }], answer: false } } var filtered = {}; Object.keys(result).forEach(function(item) { if (result[item].answer === true) { filtered[item] = result[item]; } }); console.log(filtered); 

Answer 2

You can use the Lodash pickBy function like this:

_.pickBy(result, function(c){return c.answer});

pickBy "creates an object composed of the object properties predicate returns truthy for" ( docs ). In your example, you want an object with the cases for which answer is truthy, so the predicate just returns that value.

Answer 3

Object.keys() gives you the keys of your array and allows you to iterate through the properties. Then you can filter them based on your criterion and add the correct properties to a new object.

var out = {};

Object.keys(result).filter(function(item) {
    return result[item].answer === true;
}).map(function(item) {
    out[item] = result[item];
});

Docs

• Object.keys()
• Array.prototype.filter()
• Array.prototype.map()