With AngularJS 1.7 the data-src attribute of an image gets automatically replaced

[fbrandel]

I'm submitting a ...

• bug report

Current behavior:
The data-src attribute of an image gets replaced with the value of the src attribute

Expected:
The data-src attribute contains the original value.
As the image is plain HTML, and has no obvious directives bound to it, I would expect that nothing is changed for this element. With version 1.7 this somehow changed.

Steps to reproduce
See Plunker (http://plnkr.co/edit/bpouxUmsXretMfcb)

• With AngularJS version 1.7 the data-src attribute changes to the value of the src attribute (Red border)
• With AngularJS version 1.6 the data-src attribute contains the original value (Green border)

AngularJS version: 1.7.x
Browser: all

[petebacondarwin]

This was introduced in dedb10c by our work on adding support for arbitrary property and event bindings.

It seems that we map src and data-src to the same src property on $attrs - then there is a watch handler on the src value, which then writes back to src and data-src.

Any thoughts @jbedard?

[jbedard]

@petebacondarwin you sure it was dedb10c not something earlier like 1e9eadc? From a quick test the plnkr seems to still have the issue when changing to v1.7.0 but not v1.6.10... (either way I'm interested in investigating more).

From my initial investigation... seems like we're settings 2 $interpolate watchers on the img[src]. One reads img[src], one reads img[data-src] and both assign to the src. In this case data-src just happens to come second and overwrites the first.

I'm pretty sure we shouldn't even be creating that interpolate directive since there's no interpolation in those attributes. But the trustedContext is "mediaUrl" (since 1e9eadc?) so contextAllowsConcatenation is true and we don't exit. Do we need an interpolate function on a constant/no-interpolation src property? What should a constant/no-interpolation data- prefixed attribute do?

[petebacondarwin]

Oops. yes it was not your commit @jbedard ! It is a problem with 1.7.0.rc.0 too.

[petebacondarwin]

I agree we should not have a directive on a non-interpolated attribute.

[petebacondarwin]

Hopefully #16737 will fix this