Function patchError

packages/zone.js/lib/common/error-rewrite.ts:15–421

(Zone: ZoneType)

import {ZoneType} from '../zone-impl';

export function patchError(Zone: ZoneType): void {
  Zone.__load_patch('Error', (global: any, Zone: ZoneType, api: _ZonePrivate) => {
    /*
     * This code patches Error so that:
     *   - It ignores un-needed stack frames.
     *   - It Shows the associated Zone for reach frame.
     */

    const enum FrameType {
      /// Skip this frame when printing out stack
      zoneJsInternal,
      /// This frame marks zone transition
      transition,
    }

    const zoneJsInternalStackFramesSymbol = api.symbol('zoneJsInternalStackFrames');
    const NativeError = (global[api.symbol('Error')] = global['Error']);
    // Store the frames which should be removed from the stack frames
    const zoneJsInternalStackFrames: {[frame: string]: FrameType} = {};
    // We must find the frame where Error was created, otherwise we assume we don't understand stack
    let zoneAwareFrame1: string;
    let zoneAwareFrame2: string;
    let zoneAwareFrame1WithoutNew: string;
    let zoneAwareFrame2WithoutNew: string;
    let zoneAwareFrame3WithoutNew: string;

    global['Error'] = ZoneAwareError;
    const stackRewrite = 'stackRewrite';

    type ZoneJsInternalStackFramesPolicy = 'default' | 'disable' | 'lazy';
    const zoneJsInternalStackFramesPolicy: ZoneJsInternalStackFramesPolicy =
      global['__Zone_Error_BlacklistedStackFrames_policy'] ||
      global['__Zone_Error_ZoneJsInternalStackFrames_policy'] ||
      'default';

    interface ZoneFrameName {
      zoneName: string;
      parent?: ZoneFrameName;
    }

    function buildZoneFrameNames(zoneFrame: _ZoneFrame) {
      let zoneFrameName: ZoneFrameName = {zoneName: zoneFrame.zone.name};
      let result = zoneFrameName;
      while (zoneFrame.parent) {
        zoneFrame = zoneFrame.parent;
        const parentZoneFrameName = {zoneName: zoneFrame.zone.name};
        zoneFrameName.parent = parentZoneFrameName;
        zoneFrameName = parentZoneFrameName;
      }
      return result;
    }

    function buildZoneAwareStackFrames(
      originalStack: string,
      zoneFrame: _ZoneFrame | ZoneFrameName | null,
      isZoneFrame = true,
    ) {
      let frames: string[] = originalStack.split('\n');