JS-0116 · `async function` should have `await` expression

async function should have await expression JS-0116

Bug risk

Minor

3 months ago — 2 years old

Found async function without any await expressions

572        return await this.updateWorkItem(config, patchDoc);
573    }
574
575    async updateWorkItem(config, patchDoc) {576        return this.getWorkItem(config).then(async (workItem) => {577            if (!workItem) {578                if (!!config.ado.autoCreate) {579                    log.warn(`Warning: cannot find work item (GitHub Issue #${config.issue.number}). Creating.`);580                    workItem = await this.createWorkItem(config, true);581                } else {582                    log.warn(`Warning: cannot find work item (GitHub Issue #${config.issue.number}). Canceling update.`);583                    return 0;584                }585            }586587            let conn = this.getConnection(config);588            let client = await conn.getWorkItemTrackingApi();589            let result = null;590591            try {592                result = await client.updateWorkItem([], patchDoc, workItem.id, config.ado.project, false, config.ado.bypassRules);593            594                log.debug(result);595                log.info("Successfully updated work item:", result.id);596            597                return result;598            } catch (exc) {599                log.error("Error: failure updating work item.");600                log.error(exc);601                core.setFailed(exc);602                return -1;603            }604        });605    }606
607    async updateIssues(config) {
608        log.info("Updating issues...");

Found async function without any await expressions

gitsync.js

480        return await this.updateWorkItem(config, patchDoc);
481    }
482
483    async unlabelWorkItem(config) {484        log.info("Removing label from work item...");485486        return this.getWorkItem(config).then(async (workItem) => {487            if (!workItem) {488                log.warn(`Warning: cannot find work item (GitHub Issue #${config.issue.number}). Canceling update.`);489                return 0;490            }491492            let patchDoc = [493                {494                    op: "replace",495                    path: "/fields/System.Tags",496                    value: workItem.fields["System.Tags"].replace(this.createLabels("", [config.label]), "")497                },498                {499                    op: "add",500                    path: "/fields/System.History",501                    value: `GitHub issue #${config.issue.number}: <a href="${this.cleanUrl(config.issue.url)}" target="_new">${config.issue.title}</a> in <a href="${this.cleanUrl(config.issue.repository_url)}" target="_blank">${config.repository.full_name}</a> removal of label '${config.label.name}' by <a href="${config.issue.user.html_url}" target="_blank">${config.issue.user.login}</a>`502                }503            ];504505            return await this.updateWorkItem(config, patchDoc);506        });507    }508
509    async assignWorkItem(config) {
510        log.info("Assigning work item...");

Found async function without any await expressions

gitsync.js

251        }
252    }
253
254    async createWorkItem(config, skipQuery = false) {255        log.info("Creating work item...");256257        return this.getWorkItem(config, skipQuery).then(async (workItem) => {258            if (!!workItem) {259                log.warn(`Warning: work item (#${workItem.id}) already exists. Canceling creation.`);260                return 0;261            }262263            let converter = new showdown.Converter();264            const html = converter.makeHtml(config.issue.body);265            266            converter = null;267268            // create patch doc269            let patchDoc = [270                {271                    op: "add",272                    path: "/fields/System.Title",273                    value: `GH #${config.issue.number}: ${config.issue.title}`274                },275                {276                    op: "add",277                    path: "/fields/System.Description",278                    value: (!!html ? html : "")279                },280                {281                    op: "add",282                    path: "/fields/Microsoft.VSTS.TCM.ReproSteps",283                    value: (!!html ? html : "")284                },285                {286                    op: "add",287                    path: "/fields/System.Tags",288                    value: this.createLabels(`GitHub Issue;GitHub Repo: ${config.repository.full_name};`, config.issue.labels)289                },290                {291                    op: "add",292                    path: "/relations/-",293                    value: {294                    rel: "Hyperlink",295                    url: this.cleanUrl(config.issue.url)296                    }297                },298                {299                    op: "add",300                    path: "/fields/System.History",301                    value: `GitHub issue #${config.issue.number}: <a href="${this.cleanUrl(config.issue.url)}" target="_new">${config.issue.title}</a> created in <a href="${this.cleanUrl(config.issue.repository_url)}" target="_blank">${config.repository.full_name}</a> by <a href="${config.issue.user.html_url}" target="_blank">${config.issue.user.login}</a>`302                }303            ]304305            // set assigned to306            if (!!config.ado.assignedTo) {307                patchDoc.push({308                    op: "add",309                    path: "/fields/System.AssignedTo",310                    value: this.getAssignee(config, true)311                });312            }313314            // set area path if provided315            if (!!config.ado.areaPath) {316                patchDoc.push({317                    op: "add",318                    path: "/fields/System.AreaPath",319                    value: config.ado.areaPath320                });321            }322323            // set iteration path if provided324            if (!!config.ado.iterationPath) {325                patchDoc.push({326                    op: "add",327                    path: "/fields/System.IterationPath",328                    value: config.ado.iterationPath329                });330            }331332            // if bypass rules, set user name333            if (!!config.ado.bypassRules) {334                patchDoc.push({335                    op: "add",336                    path: "/fields/System.CreatedBy",337                    value: config.issue.user.login338                });339            }340341            log.debug("Patch document:", patchDoc);342343            let conn = this.getConnection(config);344            let client = await conn.getWorkItemTrackingApi();345            let result = null;346347            try {348                result = await client.createWorkItem([], patchDoc, config.ado.project, config.ado.wit, false, config.ado.bypassRules);349350                if (result === null) {351                    log.error("Error: failure creating work item.");352                    log.error(`WIT may not be correct: ${config.ado.wit}`);353                    core.setFailed();354                    return -1;355                }356357                log.debug(result);358                log.info("Successfully created work item:", result.id);359360                return result;361            } catch (exc) {362                log.error("Error: failure creating work item.");363                log.error(exc);364                core.setFailed(exc);365                return -1;366            }367        });368    }369
370    async closeWorkItem(config) {
371        log.info("Closing work item...");

Description

A function that does not contain any await expressions should not be async (except for some edge cases in TypeScript which are discussed below). Asynchronous functions in JavaScript behave differently than other functions in two important ways:

The return value is always a Promise.
You can use the await operator inside them.

Functions are made async so that we can use the await operator inside them. Consider this example:

async function fetchData(processDataItem) {
    const response = await fetch(DATA_URL);
    const data = await response.json();

    return data.map(processDataItem);
}

Asynchronous functions that don't use await might be an unintentional result of refactoring.

Note: This issue ignores async generator functions. Generators yield rather than return a value and async generators might yield all the values of another async generator without ever actually needing to use await.

In TypeScript, one might feel the need to make a function async to comply with type signatures defined by an interface. Ideally, the code should be refactored to get rid of such restrictions, but sometimes that isn't feasible (For example, when we are implementing an interface defined in a 3rd party library like Next.js).

This situation can easily be circumvented by returning the value with a call to Promise.resolve:

interface HasAsyncFunc {
  getNum: () => Promise<number>
}

// Not recommended:
const o: HasAsyncFunc = {
  async getNum() { return 1 }
}

// Recommended:
const o: HasAsyncFunc = {
  // We only use `Promise.resolve` to adhere to the type
  // of the surrounding object.
  getNum() { return Promise.resolve(1) }
}

It is also advised to add a comment near the redundant promise to make the intent clear.

Bad Practice

async function fetchData(): string {
    // `readFileSync` is a synchronous function that blocks
    // the main thread, and thus does not need to be `await`ed
    return fs.readFileSync("data.txt", "utf-8");
}

performAction(async () => { console.log("no awaits in here") });

a11smiles / GitSync

Bad Practice

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