Issue
I have a json from API
let a = [{"name": 'abc',"age": '23'},{"name": 'qwe',"age": '37'},{"name": 'wqewqe',"age": '27'}]
then I want to create a function to be called
public testing(data, variable){
console.log('Second name : ', data[1].variable)
}
if i called
this.testing(a,'name');
the result should be
Second name : qwe
can anyone share to me how to do it?
Thank you
Solution
In general to we have two ways to access a property of an object as shown below
someObject.propsomeObject['prop']
So, here when you want to access a property of an object by using a variable we can achieve this using bracket notation i.e., obj[<variable>] is the way.
Below is the example for the same.
let a = [{"name": 'abc',"age": '23'},{"name": 'qwe',"age": '37'},{"name": 'wqewqe',"age": '27'}];
//Provided an option to pass index as well
const printPropValue = (data, index, variable) => data[index][variable];
console.log(printPropValue(a, 1, 'name'));
console.log(printPropValue(a, 0, 'age'));
//console.log(printPropValue(a, 4, 'name')); --> Will crashIn the above approach there are some corner scenarios that need to be handled such as if the object at that index could be null or undefined. There are multiple ways in order to tackle such scenarios,
- One way is to use
Optional Chaining
let a = [{"name": 'abc',"age": '23'},{"name": 'qwe',"age": '37'},{"name": 'wqewqe',"age": '27'}];
//Provided an option to pass index as well
const printPropValue = (data, index, variable) => data[index]?.[variable];
console.log(printPropValue(a, 1, 'name'));
console.log(printPropValue(a, 0, 'age'));
console.log(printPropValue(a, 4, 'name'));- Other way using
|| (OR operator)
let a = [{"name": 'abc',"age": '23'},{"name": 'qwe',"age": '37'},{"name": 'wqewqe',"age": '27'}];
//Provided an option to pass index as well
const printPropValue = (data, index, variable) => (data[index] || {})[variable];
console.log(printPropValue(a, 1, 'name'));
console.log(printPropValue(a, 0, 'age'));
console.log(printPropValue(a, 4, 'name'));