Reference parameter in Angular 8-CodePudding

Currently, the ts code like this:

callSomeMethod(data){
  let test2 : CommonModel[] = [{ name: 'testing'}];
  data = test2;
  console.log('data');console.log(data);
}
testRef(){
  let test : CommonModel[] = [];
  this.callSomeMethod(test);
  console.log('test');console.log(test);
}

I have a 'test' variable as object/array type. I use it as parameter and call callSomeMethod(). I want to change this 'test' variable in this method.

But when finish calling, the result is still empty now.

How can I get the value correct?

CodePudding user response：

The let declaration declares a block-scoped local variable. Hence, as test is a block level variable. You have to assign back the results coming from callSomeMethod to this variable to get it updated.

test = this.callSomeMethod(test);

Live Demo (Just for a demo purpose, I removed the types from the below code snippet) :

function callSomeMethod(data) {
  let test2 = [{ name: 'testing'}];
  data = test2;
  return data;
};

function testRef() {
  let test = [];
  test = this.callSomeMethod(test);
  console.log(test);
};

testRef();

CodePudding user response：

you have to push the value to the original array,

callSomeMethod(data) {
  let test2: CommonModel[] = [{ name: 'testing' }];
  data.push(...test2);
}

testRef() {
  let test: CommonModel[] = [];
  this.callSomeMethod(test);
}

or you can return the value from callSomeMethod

callSomeMethod(): CommonModel[] {
  let test2: CommonModel[] = [{ name: 'testing' }];
  return test2;
}

testRef() {
  let test: CommonModel[] = [];
  test = this.callSomeMethod();
}