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Added NaN and (+/-)Infinity as numbers to no-inferrable-types #2885

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Jul 7, 2017
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Added NaN and (+/-)Infinity as numbers to no-inferrable-types #2885

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29c5f43
Added Infinity and -Infinity as numbers to no-inferrable-types
Jun 4, 2017
3b585b1
Used @ajaff's suggestion for isNumeric as a util
Jun 4, 2017
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9 changes: 6 additions & 3 deletions src/rules/noInferrableTypesRule.ts
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Expand Up @@ -23,6 +23,8 @@ import * as Lint from "../index";
const OPTION_IGNORE_PARMS = "ignore-params";
const OPTION_IGNORE_PROPERTIES = "ignore-properties";

const INFINITY_TEXT = "Infinity";

interface Options {
ignoreParameters: boolean;
ignoreProperties: boolean;
Expand Down Expand Up @@ -77,7 +79,8 @@ class NoInferrableTypesWalker extends Lint.AbstractWalker<Options> {
const cb = (node: ts.Node): void => {
if (shouldCheck(node, this.options)) {
const { name, type, initializer } = node;
if (type !== undefined && initializer !== undefined && typeIsInferrable(type.kind, initializer.kind)) {
if (type !== undefined && initializer !== undefined
&& typeIsInferrable(type.kind, initializer.kind, initializer.getText())) {
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consider passing initializer as parameter instead of calling getText()

const fix = Lint.Replacement.deleteFromTo(name.end, type.end);
this.addFailureAtNode(type, Rule.FAILURE_STRING_FACTORY(ts.tokenToString(type.kind)), fix);
}
Expand All @@ -104,12 +107,12 @@ function shouldCheck(node: ts.Node, { ignoreParameters, ignoreProperties }: Opti
}
}

function typeIsInferrable(type: ts.SyntaxKind, initializer: ts.SyntaxKind): boolean {
function typeIsInferrable(type: ts.SyntaxKind, initializer: ts.SyntaxKind, initializerText: string): boolean {
switch (type) {
case ts.SyntaxKind.BooleanKeyword:
return initializer === ts.SyntaxKind.TrueKeyword || initializer === ts.SyntaxKind.FalseKeyword;
case ts.SyntaxKind.NumberKeyword:
return initializer === ts.SyntaxKind.NumericLiteral;
return initializer === ts.SyntaxKind.NumericLiteral || initializerText.indexOf(INFINITY_TEXT) !== -1;
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A little helper to avoid getText(), handle negative numbers, Infinity, -Infinity, and NaN

function isNumeric(node: ts.Expression) {
    while (isPrefixUnaryExpression(node) &&
           (node.operator === ts.SyntaxKind.PlusToken || node.operator === ts.SyntaxKind.MinusToken)) {
        node = node.operand;
    }
    return node.kind === ts.SyntaxKind.NumericLiteral ||
        isIdentifier(node) && (node.text === "NaN" || node.text === "Infinity");
}

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Sure. Side note: do we want to include "NaN" for this?

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For the sake of consistency we should include NaN. Otherwise Infinity shouldn't be included either.

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👍

Also just noticed I missed an 'f' in the commit for your username. Whoops :)

case ts.SyntaxKind.StringKeyword:
switch (initializer) {
case ts.SyntaxKind.StringLiteral:
Expand Down
8 changes: 5 additions & 3 deletions test/rules/no-inferrable-types/default/test.ts.fix
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@@ -1,7 +1,9 @@
// errors, inferrable type is declared
let x = 7;
let y = false;
let z = "foo";
let a = 7;
let b = false;
let c = "foo";
let d = Infinity;
let e = -Infinity;
class C {
x = 1;
}
Expand Down
10 changes: 7 additions & 3 deletions test/rules/no-inferrable-types/default/test.ts.lint
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@@ -1,10 +1,14 @@
// errors, inferrable type is declared
let x: number = 7;
let a: number = 7;
~~~~~~ [number]
let y: boolean = false;
let b: boolean = false;
~~~~~~~ [boolean]
let z: string = "foo";
let c: string = "foo";
~~~~~~ [string]
let d: number = Infinity;
~~~~~~ [number]
let e: number = -Infinity;
~~~~~~ [number]
class C {
x: number = 1;
~~~~~~ [number]
Expand Down