Current File : /var/www/html/node_modules/eslint/lib/rules/no-plusplus.js
/**
* @fileoverview Rule to flag use of unary increment and decrement operators.
* @author Ian Christian Myers
* @author Brody McKee (github.com/mrmckeb)
*/
"use strict";
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Determines whether the given node is the update node of a `ForStatement`.
* @param {ASTNode} node The node to check.
* @returns {boolean} `true` if the node is `ForStatement` update.
*/
function isForStatementUpdate(node) {
const parent = node.parent;
return parent.type === "ForStatement" && parent.update === node;
}
/**
* Determines whether the given node is considered to be a for loop "afterthought" by the logic of this rule.
* In particular, it returns `true` if the given node is either:
* - The update node of a `ForStatement`: for (;; i++) {}
* - An operand of a sequence expression that is the update node: for (;; foo(), i++) {}
* - An operand of a sequence expression that is child of another sequence expression, etc.,
* up to the sequence expression that is the update node: for (;; foo(), (bar(), (baz(), i++))) {}
* @param {ASTNode} node The node to check.
* @returns {boolean} `true` if the node is a for loop afterthought.
*/
function isForLoopAfterthought(node) {
const parent = node.parent;
if (parent.type === "SequenceExpression") {
return isForLoopAfterthought(parent);
}
return isForStatementUpdate(node);
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "disallow the unary operators `++` and `--`",
recommended: false,
url: "https://eslint.org/docs/rules/no-plusplus"
},
schema: [
{
type: "object",
properties: {
allowForLoopAfterthoughts: {
type: "boolean",
default: false
}
},
additionalProperties: false
}
],
messages: {
unexpectedUnaryOp: "Unary operator '{{operator}}' used."
}
},
create(context) {
const config = context.options[0];
let allowForLoopAfterthoughts = false;
if (typeof config === "object") {
allowForLoopAfterthoughts = config.allowForLoopAfterthoughts === true;
}
return {
UpdateExpression(node) {
if (allowForLoopAfterthoughts && isForLoopAfterthought(node)) {
return;
}
context.report({
node,
messageId: "unexpectedUnaryOp",
data: {
operator: node.operator
}
});
}
};
}
};
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