136 lines
5.0 KiB
Plaintext
136 lines
5.0 KiB
Plaintext
/**
|
|
* @fileoverview Disallows unnecessary `return await`
|
|
* @author Jordan Harband
|
|
* @deprecated in ESLint v8.46.0
|
|
*/
|
|
"use strict";
|
|
|
|
const astUtils = require("./utils/ast-utils");
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
/** @type {import('../shared/types').Rule} */
|
|
module.exports = {
|
|
meta: {
|
|
hasSuggestions: true,
|
|
type: "suggestion",
|
|
|
|
docs: {
|
|
description: "Disallow unnecessary `return await`",
|
|
|
|
recommended: false,
|
|
|
|
url: "https://eslint.org/docs/latest/rules/no-return-await"
|
|
},
|
|
|
|
fixable: null,
|
|
|
|
deprecated: true,
|
|
|
|
replacedBy: [],
|
|
|
|
schema: [
|
|
],
|
|
|
|
messages: {
|
|
removeAwait: "Remove redundant `await`.",
|
|
redundantUseOfAwait: "Redundant use of `await` on a return value."
|
|
}
|
|
},
|
|
|
|
create(context) {
|
|
|
|
/**
|
|
* Reports a found unnecessary `await` expression.
|
|
* @param {ASTNode} node The node representing the `await` expression to report
|
|
* @returns {void}
|
|
*/
|
|
function reportUnnecessaryAwait(node) {
|
|
context.report({
|
|
node: context.sourceCode.getFirstToken(node),
|
|
loc: node.loc,
|
|
messageId: "redundantUseOfAwait",
|
|
suggest: [
|
|
{
|
|
messageId: "removeAwait",
|
|
fix(fixer) {
|
|
const sourceCode = context.sourceCode;
|
|
const [awaitToken, tokenAfterAwait] = sourceCode.getFirstTokens(node, 2);
|
|
|
|
const areAwaitAndAwaitedExpressionOnTheSameLine = awaitToken.loc.start.line === tokenAfterAwait.loc.start.line;
|
|
|
|
if (!areAwaitAndAwaitedExpressionOnTheSameLine) {
|
|
return null;
|
|
}
|
|
|
|
const [startOfAwait, endOfAwait] = awaitToken.range;
|
|
|
|
const characterAfterAwait = sourceCode.text[endOfAwait];
|
|
const trimLength = characterAfterAwait === " " ? 1 : 0;
|
|
|
|
const range = [startOfAwait, endOfAwait + trimLength];
|
|
|
|
return fixer.removeRange(range);
|
|
}
|
|
}
|
|
]
|
|
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Determines whether a thrown error from this node will be caught/handled within this function rather than immediately halting
|
|
* this function. For example, a statement in a `try` block will always have an error handler. A statement in
|
|
* a `catch` block will only have an error handler if there is also a `finally` block.
|
|
* @param {ASTNode} node A node representing a location where an could be thrown
|
|
* @returns {boolean} `true` if a thrown error will be caught/handled in this function
|
|
*/
|
|
function hasErrorHandler(node) {
|
|
let ancestor = node;
|
|
|
|
while (!astUtils.isFunction(ancestor) && ancestor.type !== "Program") {
|
|
if (ancestor.parent.type === "TryStatement" && (ancestor === ancestor.parent.block || ancestor === ancestor.parent.handler && ancestor.parent.finalizer)) {
|
|
return true;
|
|
}
|
|
ancestor = ancestor.parent;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* Checks if a node is placed in tail call position. Once `return` arguments (or arrow function expressions) can be a complex expression,
|
|
* an `await` expression could or could not be unnecessary by the definition of this rule. So we're looking for `await` expressions that are in tail position.
|
|
* @param {ASTNode} node A node representing the `await` expression to check
|
|
* @returns {boolean} The checking result
|
|
*/
|
|
function isInTailCallPosition(node) {
|
|
if (node.parent.type === "ArrowFunctionExpression") {
|
|
return true;
|
|
}
|
|
if (node.parent.type === "ReturnStatement") {
|
|
return !hasErrorHandler(node.parent);
|
|
}
|
|
if (node.parent.type === "ConditionalExpression" && (node === node.parent.consequent || node === node.parent.alternate)) {
|
|
return isInTailCallPosition(node.parent);
|
|
}
|
|
if (node.parent.type === "LogicalExpression" && node === node.parent.right) {
|
|
return isInTailCallPosition(node.parent);
|
|
}
|
|
if (node.parent.type === "SequenceExpression" && node === node.parent.expressions[node.parent.expressions.length - 1]) {
|
|
return isInTailCallPosition(node.parent);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
return {
|
|
AwaitExpression(node) {
|
|
if (isInTailCallPosition(node) && !hasErrorHandler(node)) {
|
|
reportUnnecessaryAwait(node);
|
|
}
|
|
}
|
|
};
|
|
}
|
|
};
|