问题
I'm developing hybrid application that require to call window.external.notify in javascript but this js code should run in browser also. So we have to have a condition for detecting is window.external.notify is defined or undefined. So we use that code but in runtime window.external.notify shows its value is like that {...} (but can't open). Are there any way to handle it?
if(window.external !== undefined && window.external.notify !== undefined)
回答1:
You can use this:
if (typeof (window.external) !== 'undefined' && ('notify' in window.external)) {
....
}
For reasons only known to Microsoft, window.external.notify is undefined even though you can make calls to it without any issues.
来源：https://stackoverflow.com/questions/41057092/correct-condition-for-window-external-notify-is-defined