angular flat join code example

Example 1: join last element of array javascript with different value

['tom', 'dick', 'harry'].join(', ').replace(/, ([^,]*)$/, ' and $1')
> "tom, dick and harry"

Example 2: array flatten

const arr = [1, 2, [3, 4]];

// To flat single level array
arr.flat();
// is equivalent to
arr.reduce((acc, val) => acc.concat(val), []);
// [1, 2, 3, 4]

// or with decomposition syntax
const flattened = arr => [].concat(...arr);