If the arrow function does not use curly braces{}, it is equivalent to returning directly
const arr = [1, 2, 3, 4]
arr.map(i => i) // 1 ,2 ,3, 4But if I want to return an object, I cannot use the simplest form?
arr.map(i => { a: i}) // [undefined, undefined, undefined, undefined]Must be enclosed in curly braces
arr.map(i => return {{ a: i}}) // [Object, Object, Object, Object]
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Definitely cannot use {} directly, because the function body is also implemented using {}, which will be considered to have an a:1expression
The simplest way to write it is to wrap it with ()
arr.map(i => ({a: i}))
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