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WithType Interface

Adds a type symbol to a type for stronger typing.

Sealed

This type is "sealed," meaning that code outside of the library defining it should not implement or extend it. Future versions of this type may add members or make typing of readonly members more specific.

Signature​

/** @sealed */
export interface WithType<out TName extends string = string, out TKind extends NodeKind = NodeKind, out TInfo = unknown>

Type Parameters​

Parameter Constraint Default Description
TName string string Same as TreeNodeSchema's "Name" parameter.
TKind NodeKind NodeKind Same as TreeNodeSchema's "Kind" parameter.
TInfo unknown Same as TreeNodeSchema's "Info" parameter: format depends on the Kind.

Remarks​

Powers TreeNode's strong typing setup.

Example​

Narrow types for overloading based on NodeKind

function getKeys(node: TreeNode & WithType<string, NodeKind.Array>): number[];
function getKeys(node: TreeNode & WithType<string, NodeKind.Map | NodeKind.Object>): string[];
function getKeys(node: TreeNode): string[] | number[];
function getKeys(node: TreeNode): string[] | number[] {
	const schema = Tree.schema(node);
	switch (schema.kind) {
		case NodeKind.Array: {
			const arrayNode = node as TreeArrayNode;
			const keys: number[] = [];
			for (let index = 0; index < arrayNode.length; index++) {
				keys.push(index);
			}
			return keys;
		}
		case NodeKind.Map:
			return [...(node as TreeMapNode).keys()];
		case NodeKind.Object:
			return Object.keys(node);
		default:
			throw new Error("Unsupported Kind");
	}
}

Properties​

Property Alerts Modifiers Type Description
[typeNameSymbol] Deprecated readonly TName Type symbol, marking a type in a way to increase type safety via strong type checking.
[typeSchemaSymbol] readonly TreeNodeSchemaClass<TName, TKind, TreeNode, never, boolean, TInfo> Type symbol, marking a type in a way to increase type safety via strong type checking.

Property Details​

[typeNameSymbol]​

Type symbol, marking a type in a way to increase type safety via strong type checking.

This API is deprecated and will be removed in a future release.

Use typeSchemaSymbol instead.

Sealed

This type is "sealed," meaning that code outside of the library defining it should not implement or extend it. Future versions of this type may add members or make typing of readonly members more specific.

Signature​
get [typeNameSymbol](): TName;

Type: TName

[typeSchemaSymbol]​

Type symbol, marking a type in a way to increase type safety via strong type checking.

Sealed

This type is "sealed," meaning that code outside of the library defining it should not implement or extend it. Future versions of this type may add members or make typing of readonly members more specific.

Signature​
get [typeSchemaSymbol](): TreeNodeSchemaClass<TName, TKind, TreeNode, never, boolean, TInfo>;

Type: TreeNodeSchemaClass<TName, TKind, TreeNode, never, boolean, TInfo>