can someone, please explain the following:
I'm following Dan Abramov's lectures & doing the exercises.
The code works fine, however, the tests fail when the following particular function is written with curly brackets **{ }**
.
case 'toggleTodo' :
return (
state.map( (one) => {
oneTodo( one, action )
})
);
The same code works fine without curly brackets.
case 'toggleTodo' :
return (
state.map( (one) =>
oneTodo( one, action )
)
);
Here is the JsBin . Please refer to line 31 onwards.
The pair of braces forms a block , containing a list of statements. You need to use a return
statement explicitly to make the function return something.
If you omit the braces, the arrow function has a concise body , which consists solely of a single expression whose result will implicitly become the return value of the function.
case 'toggleTodo' :
return (
state.map( (one) =>
oneTodo( one, action )
)
);
is equal to:
case 'toggleTodo' :
return (
state.map( (one) => {
return oneTodo( one, action )
})
);
see the return statement
It's a fair practice to use curly brackets when there are multiple statements inside an arrow function. Use curly braces to make multiple statements a single block and avoid getting errors inside an arrow function.
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