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mhegazymhegazy
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Define Array.isArray using a type predicate
1 parent 2cd2a4a commit 1a52038

7 files changed

Lines changed: 83 additions & 9 deletions

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‎src/lib/core.d.ts‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1150,7 +1150,7 @@ interface ArrayConstructor {
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(arrayLength?: number): any[];
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<T>(arrayLength: number): T[];
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<T>(...items: T[]): T[];
1153-
isArray(arg: any): boolean;
1153+
isArray(arg: any): arg is Array<any>;
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prototype: Array<any>;
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}
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‎tests/baselines/reference/isArray.js‎

Lines changed: 19 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
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//// [isArray.ts]
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var maybeArray: number | number[];
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if (Array.isArray(maybeArray)) {
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maybeArray.length; // OK
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}
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else {
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maybeArray.toFixed(); // OK
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}
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//// [isArray.js]
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var maybeArray;
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if (Array.isArray(maybeArray)) {
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maybeArray.length; // OK
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}
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else {
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maybeArray.toFixed(); // OK
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}

‎tests/baselines/reference/isArray.symbols‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,22 @@
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=== tests/cases/compiler/isArray.ts ===
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var maybeArray: number | number[];
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>maybeArray : Symbol(maybeArray, Decl(isArray.ts, 0, 3))
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5+
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if (Array.isArray(maybeArray)) {
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>Array.isArray : Symbol(ArrayConstructor.isArray, Decl(lib.d.ts, 1166, 28))
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>Array : Symbol(Array, Decl(lib.d.ts, 1000, 23), Decl(lib.d.ts, 1171, 11))
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>isArray : Symbol(ArrayConstructor.isArray, Decl(lib.d.ts, 1166, 28))
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>maybeArray : Symbol(maybeArray, Decl(isArray.ts, 0, 3))
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maybeArray.length; // OK
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>maybeArray.length : Symbol(Array.length, Decl(lib.d.ts, 1007, 20))
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>maybeArray : Symbol(maybeArray, Decl(isArray.ts, 0, 3))
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>length : Symbol(Array.length, Decl(lib.d.ts, 1007, 20))
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}
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else {
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maybeArray.toFixed(); // OK
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>maybeArray.toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, 463, 37))
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>maybeArray : Symbol(maybeArray, Decl(isArray.ts, 0, 3))
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>toFixed : Symbol(Number.toFixed, Decl(lib.d.ts, 463, 37))
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}

‎tests/baselines/reference/isArray.types‎

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
=== tests/cases/compiler/isArray.ts ===
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var maybeArray: number | number[];
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>maybeArray : number | number[]
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5+
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if (Array.isArray(maybeArray)) {
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>Array.isArray(maybeArray) : boolean
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>Array.isArray : (arg: any) => boolean
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>Array : ArrayConstructor
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>isArray : (arg: any) => boolean
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>maybeArray : number | number[]
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maybeArray.length; // OK
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>maybeArray.length : number
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>maybeArray : number[]
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>length : number
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}
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else {
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maybeArray.toFixed(); // OK
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>maybeArray.toFixed() : string
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>maybeArray.toFixed : (fractionDigits?: number) => string
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>maybeArray : number
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>toFixed : (fractionDigits?: number) => string
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}

‎tests/baselines/reference/library_ArraySlice.symbols‎

Lines changed: 6 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -2,22 +2,22 @@
22
// Array.prototype.slice can have zero, one, or two arguments
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Array.prototype.slice();
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>Array.prototype.slice : Symbol(Array.slice, Decl(lib.d.ts, 1048, 15))
5-
>Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 31))
5+
>Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 41))
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>Array : Symbol(Array, Decl(lib.d.ts, 1000, 23), Decl(lib.d.ts, 1171, 11))
7-
>prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 31))
7+
>prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 41))
88
>slice : Symbol(Array.slice, Decl(lib.d.ts, 1048, 15))
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1010
Array.prototype.slice(0);
1111
>Array.prototype.slice : Symbol(Array.slice, Decl(lib.d.ts, 1048, 15))
12-
>Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 31))
12+
>Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 41))
1313
>Array : Symbol(Array, Decl(lib.d.ts, 1000, 23), Decl(lib.d.ts, 1171, 11))
14-
>prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 31))
14+
>prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 41))
1515
>slice : Symbol(Array.slice, Decl(lib.d.ts, 1048, 15))
1616

1717
Array.prototype.slice(0, 1);
1818
>Array.prototype.slice : Symbol(Array.slice, Decl(lib.d.ts, 1048, 15))
19-
>Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 31))
19+
>Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 41))
2020
>Array : Symbol(Array, Decl(lib.d.ts, 1000, 23), Decl(lib.d.ts, 1171, 11))
21-
>prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 31))
21+
>prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 41))
2222
>slice : Symbol(Array.slice, Decl(lib.d.ts, 1048, 15))
2323

‎tests/baselines/reference/returnTypeParameterWithModules.symbols‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -14,9 +14,9 @@ module M1 {
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return Array.prototype.reduce.apply(ar, e ? [f, e] : [f]);
1515
>Array.prototype.reduce.apply : Symbol(Function.apply, Decl(lib.d.ts, 228, 20))
1616
>Array.prototype.reduce : Symbol(Array.reduce, Decl(lib.d.ts, 1129, 93), Decl(lib.d.ts, 1136, 120))
17-
>Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 31))
17+
>Array.prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 41))
1818
>Array : Symbol(Array, Decl(lib.d.ts, 1000, 23), Decl(lib.d.ts, 1171, 11))
19-
>prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 31))
19+
>prototype : Symbol(ArrayConstructor.prototype, Decl(lib.d.ts, 1167, 41))
2020
>reduce : Symbol(Array.reduce, Decl(lib.d.ts, 1129, 93), Decl(lib.d.ts, 1136, 120))
2121
>apply : Symbol(Function.apply, Decl(lib.d.ts, 228, 20))
2222
>ar : Symbol(ar, Decl(returnTypeParameterWithModules.ts, 1, 30))

‎tests/cases/compiler/isArray.ts‎

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,9 @@
1+
var maybeArray: number | number[];
2+
3+
4+
if (Array.isArray(maybeArray)) {
5+
maybeArray.length; // OK
6+
}
7+
else {
8+
maybeArray.toFixed(); // OK
9+
}

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