## Header ### 类定义 ```typescript class Headers { static fromResponseHeaderString(headersString: string) : Headers constructor(headers?: Headers|{[name: string]: any}) append(name: string, value: string) : void delete(name: string) : void forEach(fn: (values: string[], name: string, headers: Map<string, string[]>) => void) : void get(name: string) : string has(name: string) : boolean keys() : string[] set(name: string, value: string|string[]) : void values() : string[][] toJSON() : {[name: string]: any} getAll(name: string) : string[] entries() } ``` ### 属性 - static fromResponseHeaderString(headersString: `string`) : `Headers` Returns a new Headers instance from the given DOMString of Response Headers根据传入的DOMString - append(name: `string`, value: `string`) : `void` Appends a header to existing list of header values for a given header name. - delete(name: `string`) : `void` Deletes all header values for the given name. - foreach(fn: (values: `string[]`, name: `string`, headers: `Map<string, string[]>`) => `void`) : `void` - get(name: `string`) : `string` Returns first header that matches given name. - has(name: `string`) : `boolean` Checks for existence of header by given name. - keys() : `string[]` Returns the names of the headers - set(name: `string`, value: `string`|`string[]`) : `void` Sets or overrides header value for given name. - values() : `string[][]` Returns values of all headers. - toJSON() : {[name: `string`]: `any`} Returns string of all headers. - getAll(name: `string`) : `string[]` Returns list of header values for a given name. - entries() This method is not implemented.