Class HttpHeaders

packages/common/http/src/headers.ts:24–275

 * @publicApi
 */
export class HttpHeaders {
  /**
   * Internal map of lowercase header names to values.
   */
  private headers!: Map<string, string[]>;

  /**
   * Internal map of lowercased header names to the normalized
   * form of the name (the form seen first).
   */
  private normalizedNames: Map<string, string> = new Map();

  /**
   * Complete the lazy initialization of this object (needed before reading).
   */
  private lazyInit!: HttpHeaders | Function | null;

  /**
   * Queued updates to be materialized the next initialization.
   */
  private lazyUpdate: Update[] | null = null;

  /**  Constructs a new HTTP header object with the given values.*/

  constructor(
    headers?: string | {[name: string]: string | number | (string | number)[]} | Headers,
  ) {
    if (!headers) {
      this.headers = new Map<string, string[]>();
    } else if (typeof headers === 'string') {
      this.lazyInit = () => {
        this.headers = new Map<string, string[]>();
        headers.split('\n').forEach((line) => {
          const index = line.indexOf(':');
          if (index > 0) {
            const name = line.slice(0, index);
            const value = line.slice(index + 1).trim();
            this.addHeaderEntry(name, value);
          }
        });
      };
    } else if (typeof Headers !== 'undefined' && headers instanceof Headers) {
      this.headers = new Map<string, string[]>();
      headers.forEach((value: string, name: string) => {
        this.addHeaderEntry(name, value);
      });
    } else {
      this.lazyInit = () => {
        if (typeof ngDevMode === 'undefined' || ngDevMode) {
          assertValidHeaders(headers);
        }
        this.headers = new Map<string, string[]>();
        Object.entries(headers).forEach(([name, values]) => {
          this.setHeaderEntries(name, values);
        });
      };
    }
  }