if it is in the .ts code, there should be no way, right?
ngFor is a template instruction that is directly added to the code and directly shown to the browser without being parsed by the ng engine. Give it a try:

//ngFor
let str = `
  <p *ngFor="let o of arr">{{o}}

`;
this.test.nativeElement.innerHTML = str;

so let's just for the loop, splice the data in, and put it together in jm.add_node
. Wait for the boss to answer