Compare value from array of objects to string in React Native/Javascript

Question

I'm trying to use an If statement to compare a property off of an object in an array to a String. I'm using a for-loop but for some reason, I cannot seem to trigger the conditional statement. This is the code I'm using to store the object in AsyncStorage:

onPressNext= async () => {
        if (this.state.selectedFrequency.length > 0) {
            const selectedFrequency = this.state.selectedFrequency;
            try {
                await AsyncStorage.setItem('selectedFrequency', JSON.stringify(selectedFrequency));
              } catch (error) {
                // Error saving data
              }

and this is the code I'm using to retrieve the object later:

onPressNext= async () => {

        if (this.state.selectedExclusions.length > 0) {
            try {
                const value = await AsyncStorage.getItem('selectedFrequency');
                if (value !== null) {
                  console.log(JSON.parse(value));
                  const selectedFrequency = JSON.parse(value);

                  for (let j = 0; j < selectedFrequency.length; j++) {
                    if (JSON.stringify(selectedFrequency[j].value) === 'Daily') {
                        selectedFrequency[j].splice(j, 1);
                     } else {
                        console.log(JSON.stringify(selectedFrequency[j].label));
                     }   
                 }
                }
              } catch (error) {
                // Error retrieving data
                Alert.alert(
                    error,
                    'Sorry, there was an error',
                    [
                      { text: strings.Okay, style: 'cancel' },
                    ]
                );
              }

and this is how the aray is structured:

frequency = [
    { label: strings.Daily, value: 'Daily' },
    { label: strings.Weekly, value: 'Weekly' },
    { label: strings.Monthly, value: 'Monthly' },
    { label: strings.Every_Three_Months, value: '3 Months' },
    { label: strings.three_five_Years, value: '5 Years' },
    { label: strings.Ten_Years, value: '10 Years' }
];

What I'm expecting to happen is that if the array of objects contains an item with the string value of Daily, then that item will be removed. So the for loop goes through the array, checks the values and removes any object with the value of Daily. As mentioned below I think that the problem lies within the If statement found in the for loop.

Any help would be greatly appreciated!

Not sure what you mean by "is the array named selectedFrequency instead?" Can you clarify? Also thanks for the input! — Dominic
– Dominic, Commented Oct 26, 2017 at 14:21

Ryan O'Neill · Accepted Answer · 2017-10-26 22:56:52Z

2

const selectedFrequency = JSON.parse(value);
     for (let j = 0; j < selectedFrequency.length; j++) {
           if (JSON.stringify(selectedFrequency[j].value) === 'Daily')

You're looping over the characters in the selectedFrequency string that's been returned from AsyncStorage. selectedFrequency is a string, and running a for loop over it is giving you "D", "a", "i", "l", "y". Of course there is no value method on a string so every conditional is simply comparing undefined === 'Daily'

You need to loop over your frequency object instead. i.e.:

     for (let j = 0; j < frequency.length; j++) {
           if (frequency[j].value === 'Daily')

edited Oct 26, 2017 at 22:56

answered Oct 26, 2017 at 18:09

Ryan O'Neill

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1 Comment

Dominic Over a year ago

Yep, that did it! Thanks to everyone who helped on this, I really appreciate it.

Ravi Raj · Accepted Answer · 2017-10-26 05:40:54Z

0

I think the error is happening in your if condition

In your code selectedFrequency[j].value is already a string, but your again stringifying this string which produces result like ""Daily"" !== "Daily". Hence remove that JSON.stringify and it should work

if (selectedFrequency[j].value === 'Daily')

answered Oct 26, 2017 at 5:40

Ravi Raj

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1 Comment

Dominic Over a year ago

That was my thought exactly, but when I run the code without the JSON.stringify I end up getting this error: json value {} of type nsmutabledictionary cannot be converted to nsstring. Any thoughts on why that would be happening? Thanks for the response! I can also post a screen shot of the error if that helps

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