javascript - The following code return is inconsistent with imagination, how to solve it?

Question

function has(list, item) {
  list.forEach(v => {
    if (v === item) {
        return true
    }
  })
  return false
}

console.info(has([1,2,3], 1))

How to make the result true???

Answer 1

1. The forEach loop cannot be interrupted
2. Use for loop
3. Use indexOf
4. Use ES6 includes

Answer 2

forEachThe execution of the method cannot be interrupted and all members will always be traversed
You can do this

return list.indexOf(item) !== -1;

or use forloop

Answer 3

The arrow function does not have its own this value, but inherits from the surrounding scope.

Answer 4

Actually, it’s not that the questioner doesn’t know how to implement this simple function in other ways, he just uses forEach to do it

function has(list, item) {
    let flag = false
    list.forEach(v => {
        if (v === item) {
            flag = true
        }
    })
    return flag
}

console.info(has([1, 2, 3], 1))

Because forEach's return true和return false is not the function of return value, so we can only use flag

Answer 5

function has(list, item){
    var flag = false;
    list.forEach(v => {
        if (v === item) {
            flag = true;
        }
    });
    return flag;
}

console.log(has([1, 2, 3], 1));
// true