91 lines
3.0 KiB
JavaScript
91 lines
3.0 KiB
JavaScript
/**
|
|
* @fileoverview A rule to disallow unnecessary `.call()` and `.apply()`.
|
|
* @author Toru Nagashima
|
|
*/
|
|
|
|
"use strict";
|
|
|
|
const astUtils = require("./utils/ast-utils");
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Helpers
|
|
//------------------------------------------------------------------------------
|
|
|
|
/**
|
|
* Checks whether or not a node is a `.call()`/`.apply()`.
|
|
* @param {ASTNode} node A CallExpression node to check.
|
|
* @returns {boolean} Whether or not the node is a `.call()`/`.apply()`.
|
|
*/
|
|
function isCallOrNonVariadicApply(node) {
|
|
const callee = astUtils.skipChainExpression(node.callee);
|
|
|
|
return (
|
|
callee.type === "MemberExpression" &&
|
|
callee.property.type === "Identifier" &&
|
|
callee.computed === false &&
|
|
(
|
|
(callee.property.name === "call" && node.arguments.length >= 1) ||
|
|
(callee.property.name === "apply" && node.arguments.length === 2 && node.arguments[1].type === "ArrayExpression")
|
|
)
|
|
);
|
|
}
|
|
|
|
|
|
/**
|
|
* Checks whether or not `thisArg` is not changed by `.call()`/`.apply()`.
|
|
* @param {ASTNode|null} expectedThis The node that is the owner of the applied function.
|
|
* @param {ASTNode} thisArg The node that is given to the first argument of the `.call()`/`.apply()`.
|
|
* @param {SourceCode} sourceCode The ESLint source code object.
|
|
* @returns {boolean} Whether or not `thisArg` is not changed by `.call()`/`.apply()`.
|
|
*/
|
|
function isValidThisArg(expectedThis, thisArg, sourceCode) {
|
|
if (!expectedThis) {
|
|
return astUtils.isNullOrUndefined(thisArg);
|
|
}
|
|
return astUtils.equalTokens(expectedThis, thisArg, sourceCode);
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
module.exports = {
|
|
meta: {
|
|
type: "suggestion",
|
|
|
|
docs: {
|
|
description: "disallow unnecessary calls to `.call()` and `.apply()`",
|
|
category: "Best Practices",
|
|
recommended: false,
|
|
url: "https://eslint.org/docs/rules/no-useless-call"
|
|
},
|
|
|
|
schema: [],
|
|
|
|
messages: {
|
|
unnecessaryCall: "Unnecessary '.{{name}}()'."
|
|
}
|
|
},
|
|
|
|
create(context) {
|
|
const sourceCode = context.getSourceCode();
|
|
|
|
return {
|
|
CallExpression(node) {
|
|
if (!isCallOrNonVariadicApply(node)) {
|
|
return;
|
|
}
|
|
|
|
const callee = astUtils.skipChainExpression(node.callee);
|
|
const applied = astUtils.skipChainExpression(callee.object);
|
|
const expectedThis = (applied.type === "MemberExpression") ? applied.object : null;
|
|
const thisArg = node.arguments[0];
|
|
|
|
if (isValidThisArg(expectedThis, thisArg, sourceCode)) {
|
|
context.report({ node, messageId: "unnecessaryCall", data: { name: callee.property.name } });
|
|
}
|
|
}
|
|
};
|
|
}
|
|
};
|