javascript - get nested property value by path (resistant to null/undefined)

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// custom function solution when property names don't contain '.'

function getValue(object, path) {
    return path.split('.')
               .reduce(function(value, key) {
                   return value == null ? value : value[key];
               }, object);
}


// Usage example:

var myObject = {
    name: 'John',
    metadata: {
        type: 'json',
    },
};

var metadata = getValue(myObject, 'metadata');
var type = getValue(myObject, 'metadata.type');

console.log(metadata); // { type: 'json' }
console.log(type);     // json

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// Custom function solution when property names can contain '.'

function getValue(object, path) {
    return path.reduce(function(value, key) {
        return value == null ? value : value[key];
    }, object);
}


// Usage example:

var myObject = {
    name: 'John',
    metadata: {
        type: 'json',
    },
};

var metadata = getValue(myObject, ['metadata', 'type']);

console.log(metadata); // json

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// Optional chaining - ES2020+ solution

const getValue = (object, path) => path.reduce((value, key) => value?.[key], object);


// Usage example:

const myObject = {
    name: 'John',
    metadata: {
        type: 'json',
    },
};

const metadata = getValue(myObject, ['metadata', 'type']);

console.log(metadata); // json

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// Optional chaining (ES2020) with function overloading:

const getValue$1 = (object, path) => path.reduce((value, key) => value?.[key], object);
const getValue$2 = (object, path) => getValue$1(object, path.split('.'));


// Usage example:

const myObject = {
    name: 'John',
    metadata: {
        type: 'json',
    },
};

const metadata1 = getValue$1(myObject, ['metadata', 'type']);
const metadata2 = getValue$2(myObject, 'metadata.type');

console.log(metadata1); // json
console.log(metadata2); // json

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// custom function solution when property names don't contain '.'

function getValue$1(object, key) {
    return object == null ? object : object[key];
}

function getValue$2(object, path) {
    return path.split('.').reduce(getValue$1, object);
}


// Usage example:

var myObject = {
    name: 'John',
    metadata: {
        type: 'json',
    },
};

var metadata = getValue$2(myObject, 'metadata');
var type = getValue$2(myObject, 'metadata.type');

console.log(metadata); // { type: 'json' }
console.log(type);     // json