React native Array.find is not a function

Question

I'm a junior in js development so this might be a silly question, so apologies.

I'm using firebase in my app to store my strings, I call it once when the app is loaded and keep it in memory for faster access.

Then I use strings.find to find a specific string in the array. All work find when running on iOS, but when running on Android I keep getting this weird error

TypeError: Undefined is not a function (evaluting 'this.strings.find...

Here's my data schema

{'strings': [{'name':'something', 'value':'something'} ... ]

And here's my code

getString(name) { return this.strings.find(x => x.name == name).value }

And this is where I define the object

init(onUpdated) {
    Promise.all([stringsDb.once('value'), multiLang.once('value')])
      .then(([stringsSnapshot, multiLangSnapshot]) => {

        this.strings = stringsSnapshot.value
        this.multiLang = multiLangSnapshot.value

        onUpdated(true)
      })
      .catch((err) => {
        console.log(err.stack)
        onUpdated(false)
      });
  }

my guess is (because it's asynchronous) this.strings undefined before the promise is resolved and this.strings is assigned to. Call getName after this.strings is set or check to see if it's not undefined before performing find. — Andrew Li
– Andrew Li, Commented Jun 30, 2017 at 7:27
I thought that, so I printed this.strings to the console, and it is defined already (I use callbacks to only call the find after the strings is already defined) — orelzion
– orelzion, Commented Jun 30, 2017 at 7:28

Jony-Y · Accepted Answer · 2017-07-02 07:27:17Z

3

This probably happens because the this.strings is not an array. you need to debug it and see if its actually an array or not, my guess is it returns an object, if so then you need to use a reducer or perhaps Object.values or something to convert to an array.

p.s you should use the === operator when comparing the strings

answered Jul 2, 2017 at 7:27

Jony-Y

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1 Comment

orelzion Over a year ago

Thank you!! That's was exactly it. Turns out firebase for Android doesn't return the same object as for iOS, so I'll have to convert it to arrive before using

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