Method setRequestHeader

packages/core/xhr/index.ts:267–275

(header: string, value: string)

	}

	public setRequestHeader(header: string, value: string) {
		if (this._readyState !== this.OPENED || this._sendFlag) {
			throw new Error("Failed to execute 'setRequestHeader' on 'XMLHttpRequest': " + "The object's state must be OPENED.");
		}

		if (isString(header) && isString(value)) {
			this._options.headers[header] = value;
		}
	}

	public getAllResponseHeaders(): string {
		if (this._readyState < 2 || this._errorFlag) {