167 lines
5.8 KiB
JavaScript
167 lines
5.8 KiB
JavaScript
/**
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* @fileoverview Rule to flag statements that use magic numbers (adapted from https://github.com/danielstjules/buddy.js)
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* @author Vincent Lemeunier
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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module.exports = {
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meta: {
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type: "suggestion",
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docs: {
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description: "disallow magic numbers",
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category: "Best Practices",
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recommended: false,
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url: "https://eslint.org/docs/rules/no-magic-numbers"
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},
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schema: [{
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type: "object",
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properties: {
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detectObjects: {
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type: "boolean",
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default: false
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},
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enforceConst: {
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type: "boolean",
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default: false
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},
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ignore: {
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type: "array",
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items: {
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type: "number"
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},
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uniqueItems: true
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},
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ignoreArrayIndexes: {
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type: "boolean",
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default: false
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}
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},
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additionalProperties: false
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}],
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messages: {
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useConst: "Number constants declarations must use 'const'.",
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noMagic: "No magic number: {{raw}}."
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}
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},
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create(context) {
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const config = context.options[0] || {},
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detectObjects = !!config.detectObjects,
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enforceConst = !!config.enforceConst,
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ignore = config.ignore || [],
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ignoreArrayIndexes = !!config.ignoreArrayIndexes;
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/**
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* Returns whether the node is number literal
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* @param {Node} node - the node literal being evaluated
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* @returns {boolean} true if the node is a number literal
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*/
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function isNumber(node) {
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return typeof node.value === "number";
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}
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/**
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* Returns whether the number should be ignored
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* @param {number} num - the number
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* @returns {boolean} true if the number should be ignored
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*/
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function shouldIgnoreNumber(num) {
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return ignore.indexOf(num) !== -1;
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}
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/**
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* Returns whether the number should be ignored when used as a radix within parseInt() or Number.parseInt()
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* @param {ASTNode} parent - the non-"UnaryExpression" parent
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* @param {ASTNode} node - the node literal being evaluated
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* @returns {boolean} true if the number should be ignored
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*/
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function shouldIgnoreParseInt(parent, node) {
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return parent.type === "CallExpression" && node === parent.arguments[1] &&
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(parent.callee.name === "parseInt" ||
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parent.callee.type === "MemberExpression" &&
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parent.callee.object.name === "Number" &&
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parent.callee.property.name === "parseInt");
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}
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/**
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* Returns whether the number should be ignored when used to define a JSX prop
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* @param {ASTNode} parent - the non-"UnaryExpression" parent
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* @returns {boolean} true if the number should be ignored
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*/
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function shouldIgnoreJSXNumbers(parent) {
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return parent.type.indexOf("JSX") === 0;
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}
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/**
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* Returns whether the number should be ignored when used as an array index with enabled 'ignoreArrayIndexes' option.
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* @param {ASTNode} parent - the non-"UnaryExpression" parent.
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* @returns {boolean} true if the number should be ignored
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*/
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function shouldIgnoreArrayIndexes(parent) {
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return parent.type === "MemberExpression" && ignoreArrayIndexes;
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}
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return {
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Literal(node) {
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const okTypes = detectObjects ? [] : ["ObjectExpression", "Property", "AssignmentExpression"];
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if (!isNumber(node)) {
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return;
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}
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let fullNumberNode;
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let parent;
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let value;
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let raw;
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// For negative magic numbers: update the value and parent node
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if (node.parent.type === "UnaryExpression" && node.parent.operator === "-") {
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fullNumberNode = node.parent;
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parent = fullNumberNode.parent;
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value = -node.value;
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raw = `-${node.raw}`;
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} else {
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fullNumberNode = node;
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parent = node.parent;
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value = node.value;
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raw = node.raw;
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}
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if (shouldIgnoreNumber(value) ||
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shouldIgnoreParseInt(parent, fullNumberNode) ||
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shouldIgnoreArrayIndexes(parent) ||
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shouldIgnoreJSXNumbers(parent)) {
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return;
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}
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if (parent.type === "VariableDeclarator") {
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if (enforceConst && parent.parent.kind !== "const") {
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context.report({
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node: fullNumberNode,
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messageId: "useConst"
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});
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}
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} else if (
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okTypes.indexOf(parent.type) === -1 ||
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(parent.type === "AssignmentExpression" && parent.left.type === "Identifier")
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) {
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context.report({
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node: fullNumberNode,
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messageId: "noMagic",
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data: {
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raw
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}
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});
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}
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}
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};
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}
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};
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