tools: add number-isnan rule

PR-URL: #17556
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/.eslintrc.yaml

@@ -8,6 +8,7 @@ rules:
 
   # Custom rules in tools/eslint-rules
   prefer-common-mustnotcall: 2
+  number-isnan: error
 
   ## common module is mandatory in tests
   required-modules: [error, common]

test/parallel/test-eslint-number-isnan.js

@@ -0,0 +1,20 @@
+'use strict';
+
+require('../common');
+
+const RuleTester = require('../../tools/eslint').RuleTester;
+const rule = require('../../tools/eslint-rules/number-isnan');
+
+const message = 'Please use Number.isNaN instead of the global isNaN function';
+
+new RuleTester().run('number-isnan', rule, {
+  valid: [
+    'Number.isNaN()'
+  ],
+  invalid: [
+    {
+      code: 'isNaN()',
+      errors: [{ message }]
+    }
+  ]
+});

test/parallel/test-readdouble.js

@@ -51,12 +51,12 @@ function test(clazz) {
   buffer[5] = 0xff;
   buffer[6] = 0x0f;
   buffer[7] = 0x00;
-  assert.ok(isNaN(buffer.readDoubleBE(0)));
+  assert.ok(Number.isNaN(buffer.readDoubleBE(0)));
   assert.strictEqual(2.225073858507201e-308, buffer.readDoubleLE(0));
 
   buffer[6] = 0xef;
   buffer[7] = 0x7f;
-  assert.ok(isNaN(buffer.readDoubleBE(0)));
+  assert.ok(Number.isNaN(buffer.readDoubleBE(0)));
   assert.strictEqual(1.7976931348623157e+308, buffer.readDoubleLE(0));
 
   buffer[0] = 0;

test/parallel/test-writefloat.js

@@ -106,8 +106,8 @@ function test(clazz) {
   // Darwin ia32 does the other kind of NaN.
   // Compiler bug.  No one really cares.
   assert(0x7F === buffer[7] || 0xFF === buffer[7]);
-  assert.ok(isNaN(buffer.readFloatBE(0)));
-  assert.ok(isNaN(buffer.readFloatLE(4)));
+  assert.ok(Number.isNaN(buffer.readFloatBE(0)));
+  assert.ok(Number.isNaN(buffer.readFloatLE(4)));
 }
 
 

tools/eslint-rules/number-isnan.js

@@ -0,0 +1,14 @@
+'use strict';
+
+const astSelector = "CallExpression[callee.name='isNaN']";
+const msg = 'Please use Number.isNaN instead of the global isNaN function';
+
+module.exports = function(context) {
+  function report(node) {
+    context.report(node, msg);
+  }
+
+  return {
+    [astSelector]: report
+  };
+};