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Disallow var statements (#310)
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‎src/__tests__/__snapshots__/disallowed-syntax.ts.snap

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Original file line numberDiff line numberDiff line change
@@ -11476,6 +11476,179 @@ typeof x;",
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}
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`;
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exports[`no var statements - verbose: expectParsedError 1`] = `
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Object {
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"alertResult": Array [],
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"code": "\\"enable verbose\\";
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var x = 1;",
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"displayResult": Array [],
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"errors": Array [
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NoVarError {
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"node": Node {
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"declarations": Array [
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Node {
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"end": 28,
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"id": Node {
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"end": 24,
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"loc": SourceLocation {
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"end": Position {
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"column": 6,
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"line": 2,
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},
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"start": Position {
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"column": 5,
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"line": 2,
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},
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},
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"name": "x",
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"start": 23,
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"type": "Identifier",
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},
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"init": Node {
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"end": 28,
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"loc": SourceLocation {
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"end": Position {
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"column": 10,
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"line": 2,
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},
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"start": Position {
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"column": 9,
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"line": 2,
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},
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},
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"raw": "1",
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"start": 27,
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"type": "Literal",
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"value": 1,
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},
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"loc": SourceLocation {
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"end": Position {
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"column": 10,
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"line": 2,
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},
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"start": Position {
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"column": 5,
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"line": 2,
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},
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},
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"start": 23,
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"type": "VariableDeclarator",
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},
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],
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"end": 29,
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"kind": "var",
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"loc": SourceLocation {
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"end": Position {
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"column": 11,
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"line": 2,
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},
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"start": Position {
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"column": 1,
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"line": 2,
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},
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},
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"start": 19,
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"type": "VariableDeclaration",
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},
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"severity": "Error",
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"type": "Syntax",
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},
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],
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"parsedErrors": "Line 2, Column 1: Variable declaration using \\"var\\" is not allowed.
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Use keyword \\"let\\" instead, to declare a variable:
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let x = 1;
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",
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"result": undefined,
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"resultStatus": "error",
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"visualiseListResult": Array [],
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}
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`;
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exports[`no var statements: expectParsedError 1`] = `
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Object {
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"alertResult": Array [],
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"code": "var x = 1;",
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"displayResult": Array [],
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"errors": Array [
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NoVarError {
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"node": Node {
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"declarations": Array [
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Node {
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"end": 9,
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"id": Node {
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"end": 5,
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"loc": SourceLocation {
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"end": Position {
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"column": 5,
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"line": 1,
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},
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"start": Position {
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"column": 4,
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"line": 1,
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},
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},
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"name": "x",
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"start": 4,
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"type": "Identifier",
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},
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"init": Node {
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"end": 9,
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"loc": SourceLocation {
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"end": Position {
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"column": 9,
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"line": 1,
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},
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"start": Position {
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"column": 8,
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"line": 1,
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},
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},
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"raw": "1",
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"start": 8,
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"type": "Literal",
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"value": 1,
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},
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"loc": SourceLocation {
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"end": Position {
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"column": 9,
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"line": 1,
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},
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"start": Position {
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"column": 4,
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"line": 1,
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},
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},
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"start": 4,
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"type": "VariableDeclarator",
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},
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],
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"end": 10,
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"kind": "var",
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"loc": SourceLocation {
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"end": Position {
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"column": 10,
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"line": 1,
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},
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"start": Position {
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"column": 0,
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"line": 1,
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},
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},
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"start": 0,
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"type": "VariableDeclaration",
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},
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"severity": "Error",
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"type": "Syntax",
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},
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],
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"parsedErrors": "Line 1: Variable declaration using \\"var\\" is not allowed.",
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"result": undefined,
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"resultStatus": "error",
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"visualiseListResult": Array [],
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}
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`;
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exports[`while needs braces - verbose: expectParsedError 1`] = `
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Object {
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"alertResult": Array [],

‎src/__tests__/disallowed-syntax.ts

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -435,6 +435,31 @@ For instance, to assign 20 to x, you can write:
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`)
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})
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test('no var statements', () => {
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return expectParsedError(
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stripIndent`
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var x = 1;
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`,
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{ chapter: 100 }
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).toMatchInlineSnapshot(`"Line 1: Variable declaration using \\"var\\" is not allowed."`)
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})
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test('no var statements - verbose', () => {
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return expectParsedError(
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stripIndent`
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"enable verbose";
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var x = 1;
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`,
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{ chapter: 100 }
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).toMatchInlineSnapshot(`
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"Line 2, Column 1: Variable declaration using \\"var\\" is not allowed.
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Use keyword \\"let\\" instead, to declare a variable:
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let x = 1;
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"
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`)
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})
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test('Cannot use update statements', () => {
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return expectParsedError(
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stripIndent`

‎src/rules/index.ts

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Original file line numberDiff line numberDiff line change
@@ -17,6 +17,7 @@ import noNull from './noNull'
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import noUnspecifiedLiteral from './noUnspecifiedLiteral'
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import noUnspecifiedOperator from './noUnspecifiedOperator'
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import noUpdateAssignment from './noUpdateAssignment'
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import noVar from './noVar'
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import singleVariableDeclaration from './singleVariableDeclaration'
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const rules: Array<Rule<es.Node>> = [
@@ -34,6 +35,7 @@ const rules: Array<Rule<es.Node>> = [
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noUnspecifiedLiteral,
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noUnspecifiedOperator,
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noUpdateAssignment,
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noVar,
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singleVariableDeclaration,
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noEval
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]

‎src/rules/noVar.ts

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,42 @@
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import { generate } from 'astring'
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import * as es from 'estree'
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import { ErrorSeverity, ErrorType, Rule, SourceError } from '../types'
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export class NoVarError implements SourceError {
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public type = ErrorType.SYNTAX
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public severity = ErrorSeverity.ERROR
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constructor(public node: es.VariableDeclaration) {}
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get location() {
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return this.node.loc!
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}
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public explain() {
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return 'Variable declaration using "var" is not allowed.'
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}
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public elaborate() {
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const name = (this.node.declarations[0].id as es.Identifier).name
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const value = generate(this.node.declarations[0].init)
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return `Use keyword "let" instead, to declare a variable:\n\n\tlet ${name} = ${value};`
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}
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}
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const noVar: Rule<es.VariableDeclaration> = {
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name: 'no-var',
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checkers: {
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VariableDeclaration(node: es.VariableDeclaration, ancestors: [es.Node]) {
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if (node.kind === 'var') {
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return [new NoVarError(node)]
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} else {
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return []
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}
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}
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}
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}
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export default noVar

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