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Santhanavanich authored14519e86
/** * @fileoverview Rule to check for implicit global variables, functions and classes. * @author Joshua Peek */"use strict";//------------------------------------------------------------------------------// Rule Definition//------------------------------------------------------------------------------module.exports = { meta: { type: "suggestion", docs: { description: "disallow declarations in the global scope", category: "Best Practices", recommended: false, url: "https://eslint.org/docs/rules/no-implicit-globals" }, schema: [{ type: "object", properties: { lexicalBindings: { type: "boolean", default: false } }, additionalProperties: false }], messages: { globalNonLexicalBinding: "Unexpected {{kind}} declaration in the global scope, wrap in an IIFE for a local variable, assign as global property for a global variable.", globalLexicalBinding: "Unexpected {{kind}} declaration in the global scope, wrap in a block or in an IIFE.", globalVariableLeak: "Global variable leak, declare the variable if it is intended to be local.", assignmentToReadonlyGlobal: "Unexpected assignment to read-only global variable.", redeclarationOfReadonlyGlobal: "Unexpected redeclaration of read-only global variable." } }, create(context) { const checkLexicalBindings = context.options[0] && context.options[0].lexicalBindings === true; /** * Reports the node. * @param {ASTNode} node Node to report. * @param {string} messageId Id of the message to report. * @param {string|undefined} kind Declaration kind, can be 'var', 'const', 'let', function or class. * @returns {void} */ function report(node, messageId, kind) { context.report({ node, messageId, data: { kind } }); } return { Program() { const scope = context.getScope(); scope.variables.forEach(variable => { // Only ESLint global variables have the `writable` key.
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const isReadonlyEslintGlobalVariable = variable.writeable === false;
const isWritableEslintGlobalVariable = variable.writeable === true;
if (isWritableEslintGlobalVariable) {
// Everything is allowed with writable ESLint global variables.
return;
}
variable.defs.forEach(def => {
const defNode = def.node;
if (def.type === "FunctionName" || (def.type === "Variable" && def.parent.kind === "var")) {
if (isReadonlyEslintGlobalVariable) {
report(defNode, "redeclarationOfReadonlyGlobal");
} else {
report(
defNode,
"globalNonLexicalBinding",
def.type === "FunctionName" ? "function" : `'${def.parent.kind}'`
);
}
}
if (checkLexicalBindings) {
if (def.type === "ClassName" ||
(def.type === "Variable" && (def.parent.kind === "let" || def.parent.kind === "const"))) {
if (isReadonlyEslintGlobalVariable) {
report(defNode, "redeclarationOfReadonlyGlobal");
} else {
report(
defNode,
"globalLexicalBinding",
def.type === "ClassName" ? "class" : `'${def.parent.kind}'`
);
}
}
}
});
});
// Undeclared assigned variables.
scope.implicit.variables.forEach(variable => {
const scopeVariable = scope.set.get(variable.name);
let messageId;
if (scopeVariable) {
// ESLint global variable
if (scopeVariable.writeable) {
return;
}
messageId = "assignmentToReadonlyGlobal";
} else {
// Reference to an unknown variable, possible global leak.
messageId = "globalVariableLeak";
}
// def.node is an AssignmentExpression, ForInStatement or ForOfStatement.
variable.defs.forEach(def => {
report(def.node, messageId);
});
});
}
};
}
};