Based on an array of keys, is there any way to map one object with another object?
var obj1 = { 'firstName': 'Tom', 'lastName': 'Hardy', 'age': 32 }; var obj2 = { 'firstName': 'Jon', 'lastName': 'Snow', 'age': 33 }; keys = ['lastName', 'age']; I want to update the value of lastName and age of obj1's by the obj2's value.
Is there any lodash function available for this type of mapping?
With pure Javascript you can do it using Array#forEach function to iterate over the keys and use [] notation to access the properties based on other variable's value.
var obj1 = { 'firstName': 'Tom', 'lastName': 'Hardy', 'age': 32 }; var obj2 = { 'firstName': 'Jon', 'lastName': 'Snow', 'age': 33 }; var keys = ['lastName', 'age']; keys.forEach(prop => obj1[prop] = obj2[prop]); console.log(obj1);With lodash#forEach
var obj1 = { 'firstName': 'Tom', 'lastName': 'Hardy', 'age': 32 }; var obj2 = { 'firstName': 'Jon', 'lastName': 'Snow', 'age': 33 }; var keys = ['lastName', 'age']; _.forEach(keys, prop => obj1[prop] = obj2[prop]); console.log(obj1);<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js'></script>
lodash is just a library, and it also have a function lodash.com/docs/#forEach with that you can do the same
p instead of prop.)p meant - but that suggestion was just for the OP if they were looking for maximum brevity. Regarding your Lodash suggestion, I think the OP was looking for a hypothetical _.mapProperties() type function that automatically does this for properties listed in an array, not just an alternative implementation of forEach.You can use lodash#assign and lodash#pick to achieve this result.
_.assign(obj1, _.pick(obj2, keys)); var obj1 = { 'firstName': 'Tom', 'lastName': 'Hardy', 'age': 32 }; var obj2 = { 'firstName': 'Jon', 'lastName': 'Snow', 'age': 33 }; var keys = ['lastName', 'age']; _.assign(obj1, _.pick(obj2, keys)); console.log(obj1);.as-console-wrapper{min-height:100%;top:0;}<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>Alternatively, here's an immutable solution using lodash#pick and lodash#defaults:
var result = _(obj2).pick(keys).defaults(obj1); var obj1 = { 'firstName': 'Tom', 'lastName': 'Hardy', 'age': 32 }; var obj2 = { 'firstName': 'Jon', 'lastName': 'Snow', 'age': 33 }; var keys = ['lastName', 'age']; var result = _(obj2).pick(keys).defaults(obj1); console.log(result);.as-console-wrapper{min-height:100%;top:0;}<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>