How to handle destructuring of function argument with undefined in javascript?

Question

While destructuring function argument, if the function argument is undefined how to handle it?

const product = {
    label: 'Notebook',
    price: 50
};

const destructSample = ({label, price}) => {
    console.log(label, price);
}

destructSample(product);
destructSample(undefined);

destructSample(undefined); throws following error

const destructSample = ({label, price}) => {
                         ^

TypeError: Cannot destructure property `label` of 'undefined' or 'null'.
    at destructSample (E:\PlayGround\NodeJs\nodeCourse\playground\destructuringError.js:6:24)
    at Object.<anonymous> (E:\PlayGround\NodeJs\nodeCourse\playground\destructuringError.js:11:1)
    at Module._compile (internal/modules/cjs/loader.js:701:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
    at Module.load (internal/modules/cjs/loader.js:600:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
    at Function.Module._load (internal/modules/cjs/loader.js:531:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:754:12)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)

How to resolve this? Thank you.

Answer 1

A default value can be used

 const product = { label: 'Notebook', price: 50 }; const destructSample = ({label, price}= {}) => { console.log(label, price); } destructSample(product); destructSample(undefined); 

Note:- default parameters will come into picture only when there is no arguments passed or undefined is passed as argument, so if you want to handle some more falsy value you can do something like this

 const product = { label: 'Notebook', price: 50 }; const destructSample = (obj) => { let {label, price}= obj === undefined || obj === null ? {} : obj console.log(label, price); } destructSample(product); destructSample(undefined); destructSample(); destructSample(null); 

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