Method array_from

builtin_array.go:1467–1556

(call FunctionCall)

}

func (r *Runtime) array_from(call FunctionCall) Value {
	var mapFn func(FunctionCall) Value
	if mapFnArg := call.Argument(1); mapFnArg != _undefined {
		if mapFnObj, ok := mapFnArg.(*Object); ok {
			if fn, ok := mapFnObj.self.assertCallable(); ok {
				mapFn = fn
			}
		}
		if mapFn == nil {
			panic(r.NewTypeError("%s is not a function", mapFnArg))
		}
	}
	t := call.Argument(2)
	items := call.Argument(0)
	if mapFn == nil && call.This == r.global.Array { // mapFn may mutate the array
		if arr := r.checkStdArrayIter(items); arr != nil {
			items := make([]Value, len(arr.values))
			copy(items, arr.values)
			return r.newArrayValues(items)
		}
	}

	var ctor func(args []Value, newTarget *Object) *Object
	if call.This != r.global.Array {
		if o, ok := call.This.(*Object); ok {
			if c := o.self.assertConstructor(); c != nil {
				ctor = c
			}
		}
	}
	var arr *Object
	if usingIterator := toMethod(r.getV(items, SymIterator)); usingIterator != nil {
		if ctor != nil {
			arr = ctor([]Value{}, nil)
		} else {
			arr = r.newArrayValues(nil)
		}
		iter := r.getIterator(items, usingIterator)
		if mapFn == nil {
			if a := r.checkStdArrayObjWithProto(arr); a != nil {
				var values []Value
				iter.iterate(func(val Value) {
					values = append(values, val)
				})
				setArrayValues(a, values)
				return arr
			}
		}
		k := int64(0)
		iter.iterate(func(val Value) {
			if mapFn != nil {
				val = mapFn(FunctionCall{This: t, Arguments: []Value{val, intToValue(k)}})
			}
			createDataPropertyOrThrow(arr, intToValue(k), val)
			k++
		})
		arr.self.setOwnStr("length", intToValue(k), true)
	} else {