How to replace list indexes in Javascript?

Question

I have an object in Javascript and it has some entries like:

{tempmin = 5,
tempmax= 10
}

I want to replace keys like:

.then(forecasts => {
                        this.foreCasts = forecasts.map(s => {
                            if (s.hasOwnProperty("tempmin")) {
                                s.tempmin = "Minimum Temperature"
                            }
                            if (s.hasOwnProperty("tempmax")) {
                                s.tempmax = "Maximum Temperature"
                            }
                        });

but I got the error : forecasts.map is not a function

I have checked this but it did not work. How can I replace these keys ?

.map() only works on arrays. So likely forecasts has another type. — Sirko
– Sirko, Commented May 21, 2020 at 20:25
It's not even clear what you are trying to do here. Javascript has no list data structure. The closest thing is an array, but you've posted an object (a syntactically invalid one at that). What do you mean "replace the keys"? Do you mean create a new object with a different key but the same value? — Jared Smith
– Jared Smith, Commented May 21, 2020 at 20:26
yes @JaredSmith it is an object sorry for saying list. As you said, I want to change these values and I can use a new object with correct values — abidinberkay
– abidinberkay, Commented May 21, 2020 at 20:30

user120242 · Accepted Answer · 2020-05-21 21:51:42Z

2

Destructure out tempmin, tempmax. Merge them back in as "Minimum..."

let forecasts = {
  tempmin: 5,
  tempmax: 10,
  blahblah: "x"
}

this.foreCasts = (({
  tempmin,
  tempmax,
  ...rest
}) => Object.assign(rest, {
  "Minimum Temperature": tempmin,
  "Maximum Temperature": tempmax
}))(forecasts);
console.log(this.foreCasts);

I prefer Object.assign, but you can also use spread syntax { ...rest, "Maximum Temperature": tempmin, "Maximum Temperature": tempmax }

edited May 21, 2020 at 21:51

answered May 21, 2020 at 20:26

user120242

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user120242 Over a year ago

forgot a starting parens

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