2 * @fileoverview Rule to disallow `parseInt()` in favor of binary, octal, and hexadecimal literals
3 * @author Annie Zhang, Henry Zhu
8 //------------------------------------------------------------------------------
10 //------------------------------------------------------------------------------
12 const astUtils = require("./utils/ast-utils");
14 //------------------------------------------------------------------------------
16 //------------------------------------------------------------------------------
18 const radixMap = new Map([
19 [2, { system: "binary", literalPrefix: "0b" }],
20 [8, { system: "octal", literalPrefix: "0o" }],
21 [16, { system: "hexadecimal", literalPrefix: "0x" }]
25 * Checks to see if a CallExpression's callee node is `parseInt` or
27 * @param {ASTNode} calleeNode The callee node to evaluate.
28 * @returns {boolean} True if the callee is `parseInt` or `Number.parseInt`,
31 function isParseInt(calleeNode) {
33 astUtils.isSpecificId(calleeNode, "parseInt") ||
34 astUtils.isSpecificMemberAccess(calleeNode, "Number", "parseInt")
38 //------------------------------------------------------------------------------
40 //------------------------------------------------------------------------------
47 description: "disallow `parseInt()` and `Number.parseInt()` in favor of binary, octal, and hexadecimal literals",
48 category: "ECMAScript 6",
50 url: "https://eslint.org/docs/rules/prefer-numeric-literals"
56 useLiteral: "Use {{system}} literals instead of {{functionName}}()."
63 const sourceCode = context.getSourceCode();
65 //----------------------------------------------------------------------
67 //----------------------------------------------------------------------
71 "CallExpression[arguments.length=2]"(node) {
72 const [strNode, radixNode] = node.arguments,
73 str = astUtils.getStaticStringValue(strNode),
74 radix = radixNode.value;
78 astUtils.isStringLiteral(strNode) &&
79 radixNode.type === "Literal" &&
80 typeof radix === "number" &&
81 radixMap.has(radix) &&
82 isParseInt(node.callee)
85 const { system, literalPrefix } = radixMap.get(radix);
89 messageId: "useLiteral",
92 functionName: sourceCode.getText(node.callee)
95 if (sourceCode.getCommentsInside(node).length) {
99 const replacement = `${literalPrefix}${str}`;
101 if (+replacement !== parseInt(str, radix)) {
104 * If the newly-produced literal would be invalid, (e.g. 0b1234),
105 * or it would yield an incorrect parseInt result for some other reason, don't make a fix.
107 * If `str` had numeric separators, `+replacement` will evaluate to `NaN` because unary `+`
108 * per the specification doesn't support numeric separators. Thus, the above condition will be `true`
109 * (`NaN !== anything` is always `true`) regardless of the `parseInt(str, radix)` value.
110 * Consequently, no autofixes will be made. This is correct behavior because `parseInt` also
111 * doesn't support numeric separators, but it does parse part of the string before the first `_`,
112 * so the autofix would be invalid:
114 * parseInt("1_1", 2) // === 1
120 const tokenBefore = sourceCode.getTokenBefore(node),
121 tokenAfter = sourceCode.getTokenAfter(node);
127 tokenBefore.range[1] === node.range[0] &&
128 !astUtils.canTokensBeAdjacent(tokenBefore, replacement)
135 node.range[1] === tokenAfter.range[0] &&
136 !astUtils.canTokensBeAdjacent(replacement, tokenAfter)
141 return fixer.replaceText(node, `${prefix}${replacement}${suffix}`);