How to go through an object to modify a class

Question

If given an object as a parameter to modify a created ExcelFile (using Class), how can I go through that object to find what parameter needs to be modified and then changed in the ExcelFile?

For example if I call modify({date: 12/31/2020}) I want it to update the date to 12/31/2020, however if I give it modify({date: '12/31/2020', duration: '60 minutes'}) it would update both date and duration.

My thinking was below but it is not identifying date...

class ExcelFile{
    constructor(arr){
        this.date = arr[0];
        this.duration = arr[1];
    }
    modify(obj){
        for (let key in obj) {
            if (obj[key] === "date") {
                 this.date = obj[date];
            }
        }
    }
}

"class" isn't the right term - in JS it's called "property". Object property — vsync, Apr 12 '20 at 18:13
Do you *always* want to **only** update the `date` property and no other? — vsync, Apr 12 '20 at 18:15

score 0 · Accepted Answer · answered Apr 12 '20 at 18:06

0

You are on the right track, just change the properties directly using this[key]:

class ExcelFile{
    constructor(arr){
        this.date = arr[0];
        this.duration = arr[1];
    }
    modify(obj){
        for (let key in obj) {
            this[key] = obj[key]
        }
    }
}

let file = new ExcelFile(["01/01/2020", "30 minutes"])
console.log(file)

file.modify({ date: "02/02/2020" })
console.log(file)

file.modify({ date: '12/31/2020', duration: '60 minutes' })
console.log(file)

// You can also add new properties:
file.modify({ date: '12/01/2005', size: "100 Mb" })
console.log(file)

answered Apr 12 '20 at 18:06

Anurag Srivastava

14,077
4
33
43

This is exactly what I needed. Thank you very much for answering and breaking it out in the code! – Jordan Raleigh Apr 14 '20 at 16:32
@JordanRaleigh Do accept the answer if it helped by clicking the grey tick mark next to it :) – Anurag Srivastava Apr 14 '20 at 16:33
1

Done, first question. Thanks for telling me! – Jordan Raleigh Apr 14 '20 at 16:48

vsync · Answer 2 · 2020-04-13T08:02:51.360

0

If you only need to modify the date property of your ExcelFile instance then you do not need to iterate the Object you are sending to the modify method, but you can directly access the date property of the argument via destructuring

class ExcelFile{
    constructor(arr){
        this.date = arr[0];
        this.duration = arr[1];
    }
    modify({date, duration}){
        this.date = date || this.date
        this.duration = duration || this.duration
    }
}

const file = new ExcelFile(["01/01/2020", "30 minutes"])
console.log(file)

file.modify({ date:"NEW DATE! 10/10/3000" })
console.log(file)

file.modify({ date:"foo", duration:"bar", unwanted:"baz" })
console.log(file)

edited Apr 13 '20 at 08:02

answered Apr 12 '20 at 18:24

vsync

118,978
58
307
400

OP clearly states that it can also be a `duration` property – Anurag Srivastava Apr 12 '20 at 18:34
Although I was thinking, this is a loosely typed language, isn't it just possible to do `file.date = "somevalue"` without any class method? – Anurag Srivastava Apr 13 '20 at 08:06
1

@AnuragSrivastava - your question might be related to [this topic](https://stackoverflow.com/q/22156326/104380) – vsync Apr 13 '20 at 08:32

How to go through an object to modify a class

2 Answers2