Lodash 映射对象上的键和值

Question

My code:

const orig = {" a ":1, " b ":2}
let result = _.mapKeys(_.mapValues(orig, (v) => v + 1), (v, k) => k.trim())

actual and desired result = { "a": 2, "b": 3 }

But is there a better Lodashy way of doing this?

Answer 1

This solution uses _.transform() , and it's a bit shorter. I'm not sure that it's better than your functional solution.

 const orig = {" a ": 1, " b ": 2 }; const result = _.transform(orig, (r, v, k) => { r[k.trim()] = v + 1; }); console.log(result);

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

Without lodash I would use Object.entries() to extract the key and value, map them to the required forms, and then use Object.fromEntries() to convert back to an object:

 const orig = {" a ": 1, " b ": 2 }; const result = Object.fromEntries(Object.entries(orig).map(([k, v]) => [k.trim(), v + 1])); console.log(result);

Answer 2

Just for completeness, this is how you would do it without lodash:

Solution 1: Object.keys & reduce

 const orig = {" a ":1, " b ":2}; let result = Object.keys(orig).reduce((r, k) => { r[k.trim()] = orig[k] + 1; return r; }, {}) console.log(result);

Solution 2: Object.entries & reduce

If your okay with using a polyfill for IE, you can also do this:

 const orig = {" a ":1, " b ":2}; let result = Object.entries(orig).reduce((r, [k, v]) => { r[k.trim()] = v + 1; return r; }, {}) console.log(result);

Solution 3: Object.keys/ Object.entries with Array.forEach

One of the main issues with the above approaches is that you need to return result with reduce statements. It's not a big issue, but adds to the number of lines. An alternative approach is as follows

 const orig = {" a ":1, " b ":2}; let result = {}; Object.keys(orig).forEach(k => result[k.trim()] = orig[k] + 1); console.log(result);

or

 const orig = {" a ":1, " b ":2}; let result = {}; Object.entries(orig).forEach(([k, v]) => result[k.trim()] = v + 1); console.log(result);

Answer 3

How about something like this?

 const orig = {" a ":1, " b ":2}; function test(object) { let out = {}; _.forEach(object, function(value, key) { out[key.trim()] = value + 1; }); return out; } console.log(test(orig));

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

Answer 4

Using reduce you can do:

 var obj = {" a ":1, " b ":2} result = _.reduce(obj, (result, v, k) => { result[k.trim()] = v + 1 return result }, {}) console.log(result)

 <script src="https://cdn.jsdelivr.net/npm/lodash@latest/lodash.min.js"></script>

reduce is more familiar but IMO transform seems more appropriate here

Answer 5

You could use a good ol' for in loop as it looks cleaner

const orig = {" a ":1, " b ":2};
let result = {};
for (const key in orig) {
  result[key.trim()] = orig[key] + 1
}
// result {a: 2, b: 3} 

you could even make it a one liner.. :)

const orig = { ' a ': 1, ' b ': 2 };
let result = {}; for (const key in orig) result[key.trim()] = orig[key] + 1;
// result {a: 2, b: 3}