Want to implement search any string or values inside textfile

var file = event.target.files[0];
let reader = new FileReader();
reader.onload = (e: any) => {
  // The file's text will be printed here
  
	$scope.fileContent = Reader.result;
	$scope.fileName = document.getElementById("fileinput").files[0].name;
	$scope.fileSize = document.getElementById("fileinput").files[0].size;
	
	if(data.includes('Search String')){
		console.log(data)
  }
  
  this.content = e.target.result;
};

reader.readAsText(file);