title: React/React Native + Typescript Error: Cannot find name 'INSERT FUNCTION NAME HERE'
body: <p>I'm just diving into Typescript and trying to implement it into one of my projects. However, I'm getting an error <code>Cannot find name 'selectValue'</code> when hovering over the <code>selectValue</code> method (See image below). Am I missing something in my tsconfig.json??</p>
  
  <p><strong>tsconfig.json:</strong></p>
  
  <pre><code>{
    "compilerOptions": {
      /* Basic Options */
      "target": "esnext",                       /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
      "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
      "lib": ["es6"],                           /* Specify library files to be included in the compilation. */
      "allowJs": true,                          /* Allow javascript files to be compiled. */
      // "checkJs": true,                       /* Report errors in .js files. */
      "jsx": "react-native",                    /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
      // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
      // "sourceMap": true,                     /* Generates corresponding '.map' file. */
      // "outFile": "./",                       /* Concatenate and emit output to single file. */
      // "outDir": "./",                        /* Redirect output structure to the directory. */
      // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
      // "removeComments": true,                /* Do not emit comments to output. */
      "noEmit": true,                           /* Do not emit outputs. */
      "incremental": true,                      /* Enable incremental compilation */
      // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
      // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
      "isolatedModules": true,                  /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
  
      /* Strict Type-Checking Options */
      "strict": true,                           /* Enable all strict type-checking options. */
      // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
      // "strictNullChecks": true,              /* Enable strict null checks. */
      "strictFunctionTypes": true,              /* Enable strict checking of function types. */
      // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
      // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
      // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
  
      /* Additional Checks */
      // "noUnusedLocals": true,                /* Report errors on unused locals. */
      // "noUnusedParameters": true,            /* Report errors on unused parameters. */
      // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
      // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
  
      /* Module Resolution Options */
      "moduleResolution": "node",               /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
      "baseUrl": "./",                          /* Base directory to resolve non-absolute module names. */
      // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
      // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
      "typeRoots": [                            /* List of folders to include type definitions from. */
  
      ],
      "types": [                                /* Type declaration files to be included in compilation. */
        "react",
        "react-native"
      ],
      "allowSyntheticDefaultImports": true,     /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
      "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
      // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
  
      /* Source Map Options */
      // "sourceRoot": "./",                    /* Specify the location where debugger should locate TypeScript files instead of source locations. */
      // "mapRoot": "./",                       /* Specify the location where debugger should locate map files instead of generated locations. */
      // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
      // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
  
      /* Experimental Options */
      // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
      // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
    },
    "exclude": [
      "node_modules",
      "babel.config.js",
      "metro.config.js",
      "jest.config.js"
    ]
  }
  </code></pre>
  
  <p><strong>Component:</strong></p>
  
  <pre><code>// Imports: Dependencies
  import React, { useState } from 'react';
  import { Dimensions, Platform, Picker, StyleSheet, Text, View, TouchableOpacity } from 'react-native';
  // import DateTimePicker from '@react-native-community/datetimepicker';
  import Modal from 'react-native-modal';
  import Icon from 'react-native-vector-icons/Ionicons';
  Icon.loadFont();
  
  // Screen Dimensions
  const { height, width } = Dimensions.get('window');
  
  // Component: List Picker
  export const ListPicker = (props: object) =&gt; {
    // React Hooks: State
    const [ modalVisible, toggle ] = useState(false);
    const [ value, setValue ] = useState();
  
    // React Hooks: Lifecycle Methods
  
    // Toggle Modal
    toggleModal = () =&gt; {
      try {
        // Check Platform (iOS)
        if (Platform.OS === 'ios') {
          // React Hook: Toggle Modal
          toggle((modalVisible) =&gt; !modalVisible);
        }
  
        // Check Platform (Android)
        if (Platform.OS === 'android') {
  
        };
      }
      catch (error) {
        console.log(error);
      }
    };
  
    // Select Value
    selectValue = (value: string) =&gt; {
      try {
        // React Hook: Set Value
        setValue(value);
  
        // React Props: onValueChange
        props.onValueChange(value);
      }
      catch (error) {
        console.log(error);
      }
    };
  
    // Render Picker
    renderPicker = () =&gt; {
      try {
        return (
          &lt;Picker
            selectedValue={value}
            onValueChange={this.selectValue}&gt;
            {props.items.map((item: object) =&gt; {
              return (
                &lt;Picker.Item
                  label={item.label}
                  value={item.value}
                  key={item.key || item.label}
                  color={item.color}
                /&gt;
              );
            })}
          &lt;/Picker&gt;
        )
      }
      catch (error) {
        console.log(error);
      }
    };
  
    return (
      &lt;View style={styles.container}&gt;
        &lt;View style={styles.inputTitleContainer}&gt;
        &lt;Text style={styles.inputTitle}&gt;{props.title}&lt;/Text&gt;
        &lt;/View&gt;
  
        &lt;TouchableOpacity onPress={this.toggleModal} style={styles.fieldTextContainer}&gt;
          &lt;Text style={styles.fieldText} numberOfLines={1}&gt;{value !== undefined ? value : 'Select'}&lt;/Text&gt;
  
          &lt;Icon name="ios-arrow-forward" size={22} style={styles.arrowForward}/&gt;
        &lt;/TouchableOpacity&gt;
  
        &lt;Modal isVisible={modalVisible} style={styles.modal}&gt;
          &lt;View style={styles.modalContainer}&gt;
            &lt;View style={styles.pickerHeaderContainer}&gt;
              &lt;TouchableOpacity onPress={this.toggleModal} &gt;
                &lt;Text style={styles.doneText}&gt;Done&lt;/Text&gt;
              &lt;/TouchableOpacity&gt;
            &lt;/View&gt;
  
            &lt;View style={styles.pickerContainer}&gt;
              {this.renderPicker()}
            &lt;/View&gt;
          &lt;/View&gt;
        &lt;/Modal&gt;
      &lt;/View&gt;
    );
  }
  
  // Styles
  const styles = StyleSheet.create({
    container: {
      display: 'flex',
      width: width - 32,
      marginLeft: 16,
      marginRight: 16,
      justifyContent: 'center',
    },
    modal: {
      margin: 0,
    },
    modalContainer: {
      height: '100%',
      alignItems: 'center',
      justifyContent: 'flex-end',
    },
    pickerHeaderContainer: {
      display: 'flex',
      flexDirection: 'row',
      justifyContent: 'flex-end',
      alignItems: 'center',
      height: 40,
      width: width,
      backgroundColor: '#FAFAF8',
      borderColor: '#7D7D7D',
      borderBottomWidth: StyleSheet.hairlineWidth,
    },
    pickerContainer: {
      height: 220,
      width: width,
      // backgroundColor: '#CFD3D9',
      backgroundColor: 'white',
    },
    doneText: {
      fontFamily: 'System',
      color: '#007AFF',
      fontWeight: '600',
      fontSize: 17,
      marginRight: 16,
    },
    stateContainer: {
      alignItems: 'center',
      width: 75,
      borderColor: '#7D7D7D',
      borderBottomWidth: StyleSheet.hairlineWidth,
    },
    inputTitleContainer: {
      width: 75,
      marginBottom: 4,
    },
    inputTitle: {
      color: '#7D7D7D',
      borderColor: '#7D7D7D',
      fontSize: 10,
      fontWeight: '600',
      textTransform: 'uppercase',
    },
    fieldTextContainer: {
      height: 40,
      display: 'flex',
      flexDirection: 'row',
      justifyContent: 'space-between',
      alignItems: 'center',
      marginBottom: 4,
      borderColor: '#7D7D7D',
      borderBottomWidth: StyleSheet.hairlineWidth,    
    },
    fieldText: {
      width: width - 32 - 20,
      fontFamily: 'System',
      fontSize: 17,
      fontWeight: '400',
      color: '#000000',
      alignSelf: 'center',
    },
    arrowForward: {
      color: 'black',
      opacity: .3,
      marginRight: 7,
    },
  });
  </code></pre>
  
  <p><strong>Screenshot:</strong></p>
  
  <p><a href="https://i.stack.imgur.com/tJImQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tJImQ.png" alt="enter image description here"></a></p>