Remove blank attributes from an Object in Javascript
How do I remove all attributes which are undefined or null in a JavaScript object?
(Question is similar to this one for Arrays)
You can loop through the object:
var test = {
test1 : null,
test2 : 'somestring',
test3 : 3,
}
function clean(obj) {
for (var propName in obj) {
if (obj[propName] === null || obj[propName] === undefined) {
delete obj[propName];
}
}
}
clean(test);
If you're concerned about this property removal not running up object's proptype chain, you can also:
function clean(obj) {
var propNames = Object.getOwnPropertyNames(obj);
for (var i = 0; i < propNames.length; i++) {
var propName = propNames[i];
if (obj[propName] === null || obj[propName] === undefined) {
delete obj[propName];
}
}
}
A few notes on null vs undefined:
test.test1 === null; // true
test.test1 == null; // true
test.notaprop === null; // false
test.notaprop == null; // true
test.notaprop === undefined; // true
test.notaprop == undefined; // true
Using some ES6 / ES2015 :
1) A simple one-liner to remove the items inline without assignment:
Object.keys(myObj).forEach((key) => (myObj[key] == null) && delete myObj[key]);
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2) This example was removed...
3) First example written as a function:
const removeEmpty = (obj) => {
Object.keys(obj).forEach((key) => (obj[key] == null) && delete obj[key]);
}
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4) This function uses recursion to delete items from nested objects as well:
const removeEmpty = (obj) => {
Object.keys(obj).forEach(key => {
if (obj[key] && typeof obj[key] === 'object') removeEmpty(obj[key]);
else if (obj[key] == null) delete obj[key];
});
};
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4b) This is similar to 4), but instead of mutating the source object directly, it returns a new object.
const removeEmpty = (obj) => {
const o = JSON.parse(JSON.stringify(obj)); // Clone source oect.
Object.keys(o).forEach(key => {
if (o[key] && typeof o[key] === 'object')
o[key] = removeEmpty(o[key]); // Recurse.
else if (o[key] === undefined || o[key] === null)
delete o[key]; // Delete undefined and null.
else
o[key] = o[key]; // Copy value.
});
return o; // Return new object.
};
5) A functional approach to 4b) based on @MichaelJ.Zoidl's answer using filter() and reduce() . This one returns a new object as well:
const removeEmpty = (obj) =>
Object.keys(obj)
.filter(k => obj[k] !== null && obj[k] !== undefined) // Remove undef. and null.
.reduce((newObj, k) =>
typeof obj[k] === 'object' ?
Object.assign(newObj, {[k]: removeEmpty(obj[k])}) : // Recurse.
Object.assign(newObj, {[k]: obj[k]}), // Copy value.
{});
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6) Same as 4) but with ES7 / 2016 Object.entries() .
const removeEmpty = (obj) =>
Object.entries(obj).forEach(([key, val]) => {
if (val && typeof val === 'object') removeEmpty(val)
else if (val == null) delete obj[key]
})
7) Same as 4) but in plain ES5 :
function removeEmpty(obj) {
Object.keys(obj).forEach(function(key) {
if (obj[key] && typeof obj[key] === 'object') removeEmpty(obj[key])
else if (obj[key] == null) delete obj[key]
});
};
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If you are using lodash or underscore.js, here is a simple solution:
var obj = {name: 'John', age: null};
var compacted = _.pickBy(obj);
This will only work with lodash 4, pre lodash 4 or underscore.js, use _.pick(obj, _.identity) ;
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