如何判断Javascript中的变量是否为空？抱歉问这个愚蠢的问题，但我是Javascript的新手！
if(response.photo) is empty {
do something
else {
do something else
}
response.photo was from JSON, and it could be empty sometimes, empty data cells! I want to check if it's empty.
如何判断Javascript中的变量是否为空？抱歉问这个愚蠢的问题，但我是Javascript的新手！
if(response.photo) is empty {
do something
else {
do something else
}
response.photo was from JSON, and it could be empty sometimes, empty data cells! I want to check if it's empty.
如果要测试空字符串:
if(myVar === ''){ // do stuff };
如果要判断已声明但未定义的变量:
if(myVar === null){ // do stuff };
如果要判断可能未定义的变量:
if(myVar === undefined){ // do stuff };
If you're checking both i.e, either variable is null or undefined:
if(myVar == null){ // do stuff };