How to create global helper function in react native?

Question

How can I create Global Helper functions in react-native?

I would like to use for accessing sqlite database or fetching data from server. Can I create a JavaScript file with functions and call that functions from multiple views?

Answer 1

The way we've done it in the past:

1. Create a file that exports a function:

   module.exports = function(variable) {    
      console.log(variable);
   }
   

2. Require the file when you want to use it, in a variable:

   var func = require('./pathtofile');
   

3. Use function:

   func('myvariable');
   

Answer 2

global variable

class MainActivity extends Component {

  constructor(){
     super();

     // Creating Global Variable.
     global.SampleVar = 'This is Global Variable.';
  }
}

in second activity

class SecondActivity extends Component {

  render(){
    return(
       <View>
          <Text> {global.SampleVar} </Text>
       </View>
   );
  }
}

But if you want to have a global function

export function TestFunc1() {

}

export function TestFunc2() {

}

Then import and use

import { TestFunc1 } from './path_to_file'

Answer 3

2 methods, not sure which one is better:

1. Method

Use:

window.foo = function(val) {
   alert(val);
}

2. (Not really global) Inside your class where you export and require in the need-to-use file, you can define your function.

See this:

var React = require('react-native');

var {
  View,
} = React;

var styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  }
});

var MoviesScreen = React.createClass({
  foo : function(val) {
    alert(val);
  },

render: function() {
    return (
      <View style={styles.container}>      
      </View>
    );
  },
});


module.exports = MoviesScreen;

Answer 4

I have this helper function:

function myfunction(foo)

I declare it globally as:

global.myfunction = function myfunction(foo) {...};

Answer 5

I did in a simple way like this:

1. I created a helpers.js file that will contain all the helper functions for my project & placed it like this: ./src/helpers.js(you can place anywhere you like).

2. Exported the function like this from helpers.js:

   export function GlobalLogout(str) {.....}

3. Then I imported the function like this:

   import { GlobalLogout } from '../src/helpers';

4. And finally use the function in the file like this:

   GlobalLogout(data);

Hope this helps anyone!