How to write code in functional way in Js

Question

How do we write code in a functional manner inside Javascript?

So what I initially did was something like this

render ()  {

    if (!this.props.mainListFetching && !this.props.mainListError) {
      let testData = this.sortAmountPledgingMaximumOrMinimum(this.props.mainList, "maximum")
      console.log(testData) //Coming out to be undefined
        this.sortTypeTownOrCountry(this.props.mainList)
        this.sortPercentHighestOrLeast(this.props.mainList)

    }

this calls the following function

 sortPercentHighestOrLeast = (data, type) => {
       data.sort((a, b) => {
           if (type == "maximum") {
            return (
                a["percentage.funded"] - b["percentage.funded"]
            )
        } else {
            return (
                b["percentage.funded"] - a["percentage.funded"]
            )
        }
     }) 
     console.log(data)
     return data
}

I was expecting the result from the above function will be saved in my testData variable but when I console.log, it is coming out to be undefined.

My console.log(data) is printing result in console which confirms that function is executing and data isn't undefined?

[Update:] I have also tried this (since Js is async)

 let testData =  this.sortAmountPledgingMaximumOrMinimum(this.props.mainList, "maximum", (data) => {
            console.log("anything") //Doesn't log anything
          })

Looks odd, are you sure that's the exact code you're using? Can you post a live minimal reproducible example that illustrates the problem? If data.sort doesn't throw an error due to data being undefined, then the function should return something that isn't undefined — CertainPerformance
– CertainPerformance, Commented Nov 10, 2018 at 21:42
Shouldn't a["percentage.funded"] be a.percentage.funded? Are you sure the key is "percentage.funded"? BTW, sort mutates the original array. — ibrahim mahrir
– ibrahim mahrir, Commented Nov 10, 2018 at 21:46
Do note that .sortAmountPledgingMaximumOrMinimum (what generates testData) is not the same function as sortPercentHighestOrLeast (the function you posted in the second code block). What is sortAmountPledgingMaximumOrMinimum? — CertainPerformance
– CertainPerformance, Commented Nov 10, 2018 at 21:47
Then the problem is in sortAmountPledgingMaximumOrMinimum() — Nikko Khresna
– Nikko Khresna, Commented Nov 10, 2018 at 21:52
I don't there is a problem any more @CertainPerformance as it was the wrong function name... The OP said "That fixed it". — Andy
– Andy, Commented Nov 10, 2018 at 21:59

Nina Scholz · Accepted Answer · 2018-11-10 21:58:04Z

3

Assuming funded is a nested property of percentage, you could move the check of the condition a step ahead because you check for each sorting iteration.

sortPercentHighestOrLeast = (data, type) => data.sort(type => type === "maximum"
    ? (a, b) => a.percentage.funded - b.percentage.funded
    : (a, b) => b.percentage.funded - a.percentage.funded
);

answered Nov 10, 2018 at 21:58

Nina Scholz

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3 Comments

Alwaysblue Over a year ago

are you sure it will work? For some reason i don't see any changes in my data

Nina Scholz Over a year ago

you don't even add your data to the question, so i assume, it should work. btw, why do you assume to get an answer without supplying data of the array?

Alwaysblue Over a year ago

Sorry my bad and thanks for answering the question. btw - I think original question didn't actually require you to have data since console.log of the function was logging something but when I was doing console.log(testData) it was coming out to be undefined. @CertainPerformance pointed out my mistake in comment section.

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