Why @esri/arcgis-rest-js?

@esri/arcgis-rest-js simplifies making requests to ArcGIS Online and Enterprise in both browsers and Node.js.

There's no better way to explain what that means than comparing an @esri/arcgis-rest-js call to the same web request made using plain old JavaScript.

@esri/arcgis-rest

import { getUser } from "@esri/arcgis-rest-users";

// pass in a username and get back information about the user
getUser(`jgravois`)
  .then(response) // { firstName: "john", description: "open source geodev" ... }

vs. Vanilla JavaScript

// construct the url yourself and don't forget to tack on f=json
const url = "https://www.arcgis.com/sharing/rest/community/users/jgravois?f=json";

var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
  if (xhr.readyState == XMLHttpRequest.DONE) {
    xhr.responseText; // { firstName: "john", description: "open source geodev" ... }
  }
}
xhr.open('GET', url, true);
xhr.send(null);

wow, thats a lot easier! @esri/arcgis-rest-js is able to intuit the actual url (by default it assumes you're interacting with ArcGIS Online) prior to making the request and internalizes a lot of tedious logic for handling the response.

Our packages tap into a new JavaScript spec called fetch() under the hood though, so lets compare 🍎s to 🍎s.

import { deleteFeatures } from "@esri/arcgis-rest-feature-service";

const url = `http://sampleserver6.arcgisonline.com/arcgis/rest/services/SF311/FeatureServer/1/`

// https://esri.github.io/arcgis-rest-js/api/feature-service/deleteFeatures/
deleteFeatures({
  url,
  objectIds: [ 2360245 ]
})
  .then(response)
// append operation name to url
url += `deleteFeatures`;

fetch(url, {
  // set the request type
  method: "POST",
  // append appropriate headers
  headers: {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  // concatentate and encode each parameter manually
  // and remember to append f=json
  body: `objectIds=${encodeURIComponent(2360245)}&f=json`
})
  .then(response => {
    // cast the response as JSON
    if (response.ok) {
      return response.json()
    }
  })
  .then(response => {
    // trap for ArcGIS error objects in 200 responses
    if (!response.error) {
      console.log(response);
    }
  })

As you can see, @esri/arcgis-rest-js is still handling a lot of the details internally.

  • the operation name is appended to urls
  • a "POST" is made automatically (when appropriate)
  • query string parameters are encoded
  • appropriate headers are appended
  • FormData is created internally (when necessary)
  • 200 responses that contain an error are trapped for
  • the generic f=json parameter is appended

And we haven't even begun to discuss authentication.

Whether you're trying to automate interacting with premium services in Node.js or creating a website that will allow users to sign into ArcGIS Online safely and manage their own content, @esri/arcgis-rest-js has you covered.

Package Overview

The library is a collection of very small mix and match packages that are framework agnostic and make a variety of ArcGIS tasks more convenient.