match.md

match decorator

It allows you to set a pair (or sets of pairs) of step functions that will be executed conditionally. We call the first function the predicate (it returns a boolean) and the second one the statement step function. The latter will be executed only if the former evaluates to true. In this sense this decorator is similar to iif, however match decorator allows you to set a default statement function, that will be executed if predicate evaluates to `false'. In addition, you can "pipe" multiple pairs (predicate and statement) and have just one default statement step function for all of them. You can explore the source code here.

Example

One predicate-statement function pair

In this example the first argument of the m.on() method (our predicate function) will evaluate to false, hence the otherwise() function will be invoked.

const { match, pipe } = require('@axa/bautajs-core');

bautajsInstance.operations.v1.randomOperation.setup(
  pipe(
      () => console.log('nighter a predicate nor a statement step function'),
      match(m =>
        m
        .on((prev)=> typeof prev === 'number', () => console.log('Only meat lovers'))
        .otherwise(() => console.log('You can always eat veggies!'))
      )
    ));

// => return value of the pipeline will be an array (we piped two step functions):
// ['nighter a predicate nor a statement step function', 'You can always eat veggies!']

More than one predicate-statement function pair

Here the second predicate function evaluates to true, so the string 'I love and care about our oceans' will be logged to the console. Note that in this case otherwise() statement will not be invoked.

const { match, pipelineBuilder } = require('@axa/bautajs-core');

bautajsInstance.operations.v1.randomOperation.setup(
  pipe(
      () => return true,
      match(
        m
          .on(prev => prev === false, () => console.log('I am an ignorant and leave garbage on the beach'))
          .on(prev => prev === true, () => console.log('I love and care about our oceans'))
          .otherwise(() => null)
      )
    )
);

// => 'I love and care about our oceans'