Javascript re-assign let variable with destructuring

javascript ecmascript-6 eslint
Phil Mok picture Phil Mok · Feb 9, 2018 · Viewed 10k times · Source

In my React app I am using airbnb's eslint style guide which will throw an error if I do not use destructuing.

In the situation below, I first use let to assign the two variables latitude and longitude to the coordinates of the first item in an array of location objects. Then I try to use destructuring to re-assign their values if the user has given me access to their location.

let latitude = locations[0].coordinates[1];
let longitude = locations[0].coordinates[0];

if (props.userLocation.coords) {
  // doesn't work - unexpected token
  { latitude, longitude } = props.userLocation.coords;

  // causes linting errors
  // latitude = props.userLocation.coords.latitude;
  // longitude = props.userLocation.coords.longitude;
}

Destructuring inside the if statement causes an unexpected token error.

Re-assigning the variables the old fashioned way causes an ESlint: Use object destructuring error.

Answer

Jonas Wilms picture Jonas Wilms · Feb 9, 2018 
 ({ latitude, longitude } = props.userLocation.coords);

Destructuring needs to be either after a let, const or var declaration or it needs to be in an expression context to distinguish it from a block statement.

Related questions

eslint: error Parsing error: The keyword 'const' is reserved

I am getting this error from ESLint: error Parsing error: The keyword 'const' is reserved from this code: const express = require('express'); const app = express(); const _ = require('underscore'); I've tried removing node_modules and reinstalling all npm packages (as suggested …

Read More
Expected 'this' to be used by class method

In my class, eslint is complaining "Expected 'this' to be used by class method 'getUrlParams' Here is my class: class PostSearch extends React.Component { constructor(props) { super(props); this.getSearchResults(); } getUrlParams(queryString) { const hashes = queryString.slice(queryString.indexOf('?') + 1).…

Read More
How do I access the Object.prototype method in the following logic?

I am using the following logic to get the i18n string of the given key. export function i18n(key) { if (entries.hasOwnProperty(key)) { return entries[key]; } else if (typeof (Canadarm) !== 'undefined') { try { throw Error(); } catch (e) { Canadarm.error(…

Read More