otto/value_boolean.go

package otto

import (
    "math"
	"fmt"
	"reflect"
)

func toBoolean(value Value) bool {
	if value._valueType == valueBoolean {
		return value.value.(bool)
	}
    if value.IsUndefined() {
        return false
    }
    if value.IsNull() {
        return false
    }
	switch value := value.value.(type) {
	case bool:
        return value
	case int, int8, int16, int32, int64:
        return 0 != reflect.ValueOf(value).Int()
	case uint, uint8, uint16, uint32, uint64:
        return 0 != reflect.ValueOf(value).Uint()
	case float32:
        return 0 != value
	case float64:
        if math.IsNaN(value) || value == 0 {
            return false
        }
        return true
	case string:
		return 0 != len(value)
	}
	if value.IsObject() {
		return true
	}
    panic(fmt.Errorf("toBoolean(%T)", value.value))
}