81 lines
1.9 KiB
JavaScript
81 lines
1.9 KiB
JavaScript
/**
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* @fileoverview Rule to flag variables that are never assigned
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* @author Jacob Bandes-Storch <https://github.com/jtbandes>
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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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/** @type {import('../types').Rule.RuleModule} */
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module.exports = {
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meta: {
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type: "problem",
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dialects: ["typescript", "javascript"],
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language: "javascript",
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docs: {
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description:
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"Disallow `let` or `var` variables that are read but never assigned",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/no-unassigned-vars",
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},
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schema: [],
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messages: {
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unassigned:
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"'{{name}}' is always 'undefined' because it's never assigned.",
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},
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},
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create(context) {
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const sourceCode = context.sourceCode;
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let insideDeclareModule = false;
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return {
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"TSModuleDeclaration[declare=true]"() {
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insideDeclareModule = true;
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},
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"TSModuleDeclaration[declare=true]:exit"() {
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insideDeclareModule = false;
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},
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VariableDeclarator(node) {
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/** @type {import('estree').VariableDeclaration} */
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const declaration = node.parent;
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const shouldSkip =
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node.init ||
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node.id.type !== "Identifier" ||
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declaration.kind === "const" ||
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declaration.declare ||
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insideDeclareModule;
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if (shouldSkip) {
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return;
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}
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const [variable] = sourceCode.getDeclaredVariables(node);
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if (!variable) {
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return;
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}
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let hasRead = false;
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for (const reference of variable.references) {
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if (reference.isWrite()) {
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return;
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}
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if (reference.isRead()) {
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hasRead = true;
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}
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}
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if (!hasRead) {
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// Variables that are never read should be flagged by no-unused-vars instead
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return;
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}
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context.report({
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node,
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messageId: "unassigned",
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data: { name: node.id.name },
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});
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},
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};
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},
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};
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