Determines whether an image has a src value and an image has a src value.

Determines whether an image has a src value and an image has a src value.

At first, I thought it was undefined to determine whether the src value of an image exists.

I know this

However, we found a problem.

If ($ ('. img '). attr ('src') = 'undefined') {console. log ('image has no src value')} else {console. log ("image has src value ")}

We found that the image has never been printed 'image has no src value'

But clearly there is no src img tag on my page.

Then I looked at it and found that I had little knowledge.

Undefined is not quoted

If ($ ('. img '). attr ('src') = undefined) {console. log ('image has no src value')} else {console. log ("image has src value ")}

Mom, you can.

Blame me for reading less

You must never make such a mistake.