Angular 6 - Parsing JSON

I think your properties in the JSON are parsed from upper case to lower case - CheckName -> checkName. As Javascript/Typescript is a case sensitive language you need to different property names.

Try to log with lower case and also change your property names to start with lower case. It is a common standard in Javascript/Typescript to start function and variable/property names via lower case.

console.log(this.testResults.checkName);

You are getting undefined because this console.log(this.testResults) is fired first

RunTests() {    this._http.get<TestResult>(this._apiPath)      .subscribe(result => {      this.testResults = result;      console.log(this.testResults);      console.log(this.testResults.CheckName === undefined ? '' : this.testResults['CheckName']);    });  }

or use SetTimeOut

 RunTests() {        this._http.get<TestResult>(this._apiPath)          .subscribe(result => {          this.testResults = result;          console.log(this.testResults);         setTimeout(()=>{console.log(this.testResults['CheckName'])},2000);         });      }

I had a similar issue i.e. it looked lika valid json response but in fact it was a "text" response. Give the following a try:

  getdData(inParams) {    let headers = new HttpHeaders();    headers = headers.append('Content-Type', 'application/json');    // need responseType = text (non object)    return this.http.get(environment.url, {      headers,      responseType: 'text'    });  }