Integrating reference parameters in Angular 8

Question

Integrating reference parameters in Angular 8

The TypeScript code currently looks 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 variable named 'test' that is of object/array type. I pass it as a parameter and call the method callSomeMethod(). I want to update this 'test' variable within the method.

However, after the method call finishes, the result is still empty.

How can I correctly retrieve the updated value?

typescript angular8

Answer 1

Answer №1

When using the let declaration, a block-scoped local variable is declared. In this case, test is a block level variable. You need to reassign the results from callSomeMethod back to this variable in order to update it.

test = this.callSomeMethod(test);

Here is a Live Demo (Types have been removed for demonstration purposes) :

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

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

testRef();

Answer 2

When using the let declaration, a block-scoped local variable is declared. In this case, test is a block level variable. You need to reassign the results from callSomeMethod back to this variable in order to update it.

test = this.callSomeMethod(test);

Here is a Live Demo (Types have been removed for demonstration purposes) :

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

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

testRef();

Answer 3

Answer №2

To add the value to the original array, you must push it.

addDataToArray(data) {
  let newData: CommonModel[] = [{ name: 'new data' }];
  data.push(...newData);
}

updateArray() {
  let dataArray: CommonModel[] = [];
  this.addDataToArray(dataArray);
}

Alternatively, you can also return the value from the function.

returnData(): CommonModel[] {
  let newData: CommonModel[] = [{ name: 'new data' }];
  return newData;
}

updateArray() {
  let dataArray: CommonModel[] = [];
  dataArray = this.returnData();
}

Answer 4

To add the value to the original array, you must push it.

addDataToArray(data) {
  let newData: CommonModel[] = [{ name: 'new data' }];
  data.push(...newData);
}

updateArray() {
  let dataArray: CommonModel[] = [];
  this.addDataToArray(dataArray);
}

Alternatively, you can also return the value from the function.

returnData(): CommonModel[] {
  let newData: CommonModel[] = [{ name: 'new data' }];
  return newData;
}

updateArray() {
  let dataArray: CommonModel[] = [];
  dataArray = this.returnData();
}

Integrating reference parameters in Angular 8

Answer №1

Answer №2

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