Home > robinson > isUndefined
isUndefined() function
This API is provided as a preview for developers and may change based on feedback that we receive. Do not use this API in a production environment.
函数“isUndefined”检查值是否未定义。
Signature:
typescript
declare function isUndefined(value: any): boolean;declare function isUndefined(value: any): boolean;Parameters
| Parameter | Type | Description |
|---|---|---|
| value | any | “value”参数的类型为“any”，这意味着它可以接受任何类型的值。 |
Returns:
boolean
{boolean} 函数 isUndefined 返回一个布尔值。
Example
JavaScript
let a; isUndefined(a) // true let a; isUndefined(a) // true