When using the syntax {this.firstName, this.lastName} = this.data;, destructuring does not work as expected.
{this.firstName, this.lastName} = this.data;
The value of this.data is:
{firstName: 'joe', lastName: 'smith'}
However, after assigning the value to this.firstName and this.lastName, they are still null.
If you want to achieve destructuring without declaration, try the following:
({firstName: this.firstName, lastName: this.lastName} = this.data);
According to MDN:
The round braces ( ... ) around the assignment statement is required syntax when using object literal destructuring assignment without a declaration.
Don't forget that the TypeScript compiler will also complain if you omit the wrapping parenthesis.
Check out this example to see it in action.
I hope that explanation was clear!
In order to achieve your goal, the utilization of an object is required.
Assigning the data values to variables:
this.firstname = this.data.firstname;
this.lastName = this.data.lastname;
({firstName:this.firstName, lastName:this.lastName} = this.data);[UPDATE]
If you want to perform destructuring and assign values at the same time, use the following syntax:
{propertyNameFromObject: variableValueShouldBeAssignedTo} = someObjectTake it a step further by directly assigning the extracted value to your object property: this.firstName.
For more details, visit: (specifically section 10.8)
{first : this.first ,last : this.last } = this.data
The keys in the destructuring assignment must match the property names in the data object.
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