What is a better way of doing this. I'am assigning either of two property values (from two different objects), depending on their existence, to a third data-structure.
In case the args object's value is nullish a non nullish value gets accessed from the default object and assigned to the final structure.
return {
first: {
visible: args.first?.visible ?? defaulttest.first?.visible,
emoji: args.first?.emoji ?? defaulttest.first?.emoji,
style: args.first?.style ?? defaulttest.first?.style,
},
back: {
visible: args.back?.visible ?? defaulttest.back?.visible,
emoji: args.back?.emoji ?? defaulttest.back?.emoji,
style: args.back?.style ?? defaulttest.back?.style,
},
page: {
visible: args.page?.visible ?? defaulttest.page?.visible,
emoji: args.page?.emoji ?? defaulttest.page?.emoji,
style: args.page?.style ?? defaulttest.page?.style,
},
forward: {
visible: args.forward?.visible ?? defaulttest.forward?.visible,
emoji: args.forward?.emoji ?? defaulttest.forward?.emoji,
style: args.forward?.style ?? defaulttest.forward?.style,
},
last: {
visible: args.last?.visible ?? defaulttest.last?.visible,
emoji: args.last?.emoji ?? defaulttest.last?.emoji,
style: args.last?.style ?? defaulttest.last?.style,
},
Mdelete: {
visible: args.Mdelete?.visible ?? defaulttest.Mdelete?.visible,
emoji: args.Mdelete?.emoji ?? defaulttest.Mdelete?.emoji,
style: args.Mdelete?.style ?? defaulttest.Mdelete?.style,
},
removeBtn: {
visible: args.removeBtn?.visible ?? defaulttest.removeBtn?.visible,
emoji: args.removeBtn?.emoji ?? defaulttest.removeBtn?.emoji,
style: args.removeBtn?.style ?? defaulttest.removeBtn?.style,
},
};
From my above comments ...
1/2 ... The OP actually is not really comparing. For a certain set of properties the OP looks up each property at a target object, and only in case it features a nullish value there will be an assignment from a source object's counterpart to the missing property. Thus an approach I would choose was ...
2/2 ... implementing a generic function which merges two objects in a way that a source property can only be written/assigned in case the target structure does not already provide a non nullish value. This function then has to be invoked twice once for
argsanddefaulttestand a second time for the to be returned entirely empty data structure andargs.
The above statement was a bit ambitious for there are at least 2 strategies of how one could achieve such kind of mergers.
Thus the below provided example code implements two approaches
one, called refit, which follows a pushing/patching agenda due to forcing the assignement of every non nullish property in a source-object to its non nullish counterpart of a target-object.
a 2nd one, called revive, which resembles a pulling approach for it just reassigns the nullish target-object properties with their non nullish source-object counterparts.
The difference in the results they produce for one and the same preset is going to be demonstrated herby ...
// "refit" ... a pushing/patching approach.
// - force the assignement of every non nullish property in source
// to its non nullish counterpart in target ... hence a *refit*.
function refitNullishValuesRecursively(target, source) {
if (
// are both values array-types?
Array.isArray(source) &&
Array.isArray(target)
) {
source
// for patching always iterate the source items ...
.forEach((sourceItem, idx) => {
// ... and look whether a target counterpart exists.
if (target[idx] == null) {
// either assign an existing structured clone ...
if (sourceItem != null) {
target[idx] = cloneDataStructure(sourceItem);
}
} else {
// ... or proceed recursively.
refitNullishValuesRecursively(target[idx], sourceItem);
}
});
} else if (
// are both values object-types?
source && target &&
'object' === typeof source &&
'object' === typeof target
) {
Object
// for patching ...
.entries(source)
// ... always iterate the source entries (key value pairs) ...
.forEach(([key, sourceValue], idx) => {
// ... and look whether a target counterpart exists.
if (target[key] == null) {
// either assign an existing structured clone ...
if (sourceValue != null) {
target[key] = cloneDataStructure(sourceValue);
}
} else {
// ... or proceed recursively.
refitNullishValuesRecursively(target[key], sourceValue);
}
});
}
return target;
}
// "revive" ... a pulling approach.
// - just reassign the nullish target properties with their
// non nullish source counterparts ... hence a *revive*.
function reviveNullishValuesRecursively(target, source) {
if (
// are both values array-types?
Array.isArray(target) &&
Array.isArray(source)
) {
target
// for fixing always iterate the target items.
.forEach((targetItem, idx) => {
if (targetItem == null) {
// either assign an existing structured clone ...
target[idx] = cloneDataStructure(source[idx]) ?? targetItem;
} else {
// ... or proceed recursively.
reviveNullishValuesRecursively(targetItem, source[idx]);
}
});
} else if (
// are both values object-types?
target && source &&
'object' === typeof target &&
'object' === typeof source
) {
Object
// for fixing ...
.entries(target)
// ... always iterate the target entries (key value pairs).
.forEach(([key, targetValue], idx) => {
if (targetValue == null) {
// either assign an existing structured clone ...
target[key] = cloneDataStructure(source[key]) ?? targetValue;
} else {
// ... or proceed recursively.
reviveNullishValuesRecursively(targetValue, source[key]);
}
});
}
return target;
}
const cloneDataStructure =
('function' === typeof structuredClone)
&& structuredClone
|| (value => JSON.parse(JSON.stringify(value)));
const targetBlueprint = {
x: { xFoo: 'foo', xBar: 'bar', xBaz: { xBiz: null } },
y: { yFoo: 'foo', yBar: null },
};
const patch = {
x: { xFoo: null, xBar: null, xBaz: { xBiz: 'biz' } },
y: { yFoo: null, yBar: 'bar', yBaz: { yBiz: 'biz' } },
};
let target = cloneDataStructure(targetBlueprint);
console.log('"refit" ... a pushing/patching approach.');
console.log('before refit ...', { target, patch });
refitNullishValuesRecursively(target, patch);
console.log('after refit ...', { target, patch });
target = cloneDataStructure(targetBlueprint);
console.log('"revive" ... a pulling approach.');
console.log('before revive ...', { target, patch });
reviveNullishValuesRecursively(target, patch);
console.log('after revive ...', { target, patch });.as-console-wrapper { min-height: 100%!important; top: 0; }As for the OP's example which targets the creation of kind of a config-object, one could fully patch/refit a clone of the temporary or current args-config, whereas within the last step one has control over the config-object's final structure by providing the most basic empty config-base which just gets revived by the before created full patch/refit-config.
function refitNullishValuesRecursively(target, source) {
if (Array.isArray(source) && Array.isArray(target)) {
source
.forEach((sourceItem, idx) => {
if (target[idx] == null) {
if (sourceItem != null) {
target[idx] = cloneDataStructure(sourceItem);
}
} else {
refitNullishValuesRecursively(target[idx], sourceItem);
}
});
} else if (
source && target &&
'object' === typeof source &&
'object' === typeof target
) {
Object
.entries(source)
.forEach(([key, sourceValue], idx) => {
if (target[key] == null) {
if (sourceValue != null) {
target[key] = cloneDataStructure(sourceValue);
}
} else {
refitNullishValuesRecursively(target[key], sourceValue);
}
});
}
return target;
}
function reviveNullishValuesRecursively(target, source) {
if (Array.isArray(target) && Array.isArray(source)) {
target
.forEach((targetItem, idx) => {
if (targetItem == null) {
target[idx] = cloneDataStructure(source[idx]) ?? targetItem;
} else {
reviveNullishValuesRecursively(targetItem, source[idx]);
}
});
} else if (
target && source &&
'object' === typeof target &&
'object' === typeof source
) {
Object
.entries(target)
.forEach(([key, targetValue], idx) => {
if (targetValue == null) {
target[key] = cloneDataStructure(source[key]) ?? targetValue;
} else {
reviveNullishValuesRecursively(targetValue, source[key]);
}
});
}
return target;
}
const cloneDataStructure =
('function' === typeof structuredClone)
&& structuredClone
|| (value => JSON.parse(JSON.stringify(value)));
const defaultConfig = {
first: {
visible: 'default.first.visible',
emoji: 'default.first.emoji',
style: 'default.first.style',
},
forward: {
visible: 'default.forward.visible',
emoji: 'default.forward.emoji',
style: 'default.forward.style',
},
removeBtn: {
visible: 'default.removeBtn.visible',
emoji: 'default.removeBtn.emoji',
style: 'default.removeBtn.style',
},
};
const currentConfig = {
first: {
visible: 'current.first.visible',
emoji: 'current.first.emoji',
style: 'current.first.style',
},
forward: {
visible: 'current.forward.visible',
emoji: null,
},
FOO: {
visible: 'current.FOO.visible',
emoji: 'current.FOO.emoji',
style: 'current.FOO.style',
}
};
function getConfiguration(baseConfig) {
return reviveNullishValuesRecursively(
cloneDataStructure(baseConfig),
refitNullishValuesRecursively(
cloneDataStructure(currentConfig),
defaultConfig,
),
);
}
console.log(
getConfiguration({
first: null,
forward: null,
removeBtn: null,
})
);.as-console-wrapper { min-height: 100%!important; top: 0; }