Maps (dicts) in TypeScript

maps.ts

// When programming, there will certainly be times you will want to associate values to other values,
// that is building a dictionary.
// In TypeScript, a `Map<K, V>` exists (it seems it actually is the one defined in JavaScript ES6).
// However, at least in TypeScript 3.1.6, objects from this class are not very reliable:
// You will sometimes get errors such as "TypeError: map.get is not a function", at seemingly random times.
    
// A solution is to replace `Map<string, V>` by plain objects defined as `{ [key: string]: V }`.
// Another solution seems to be to replace them by `Record<string, V>`.
    
// This gist presents the first solution.
    
function unreliableWithMap(): void {
    let map: Map<string, string[]> = new Map();
    
    // Put a new value in the dict
    map.set('key', ['value1', 'value2']);
    
    // Remove a value
    map.delete('key');
    
    // Get a value
    const value: string[] = map.get('key');
    
    // Looping over entries
    for (const [key, value] of map.entries) {
        console.log(key, '=>', value);
    }
}
    
function reliableWithObjects(): void {
    let map: { [key: string]: string[] } = {};
    
    // Put a new value in the dict
    map['key'] = ['value1', 'value2'];
    
    // Remove a value
    delete map['key'];
    
    // Get a value
    const value: string[] = map['key'];
    
    // Looping over entries
    for (const [key, value] of Object.entries(map)) {
        console.log(key, '=>', value);
    }
}