为什么forEach（）在此对象循环中不起作用？

Question

Why forEach doesn't work for the following? I tried it a few times and it always return "unexpected token".

// for loop
for(item in items){
        if (items[item].id===idNum){
            console.log(items[item]);
        }
    }

// the for loop works. 

// forEach()

items.forEach(item=>if(item.id===idNum){console.log(item)})
// this returned error message "unexpected token"

Answer 1

Arrow functions can have either a "concise body" or the usual "block body".

In a concise body, only an expression is specified, which becomes the implicit return value. In a block body, you must use an explicit return statement

reference :- Arrow function body

Because this syntax is not correct.

items.forEach(item=>if(item.id===idNum){console.log(item)})

You need to use {} here

items.forEach(item=>{
if(item.id===idNum){console.log(item)}
})

Answer 2

You have to use brackets for function body:

 let items = [ {id:1}, {id:2} ]; let idNum = 2; items.forEach(item => { if (item.id === idNum) { console.log(item) } })