Introduce printSetInputMaxlength to properly set an inputs maxlength …

[WouterGritter]

Relates to !4295 by fixing MQTT related code that deals with the MQTT_MAX_TOPIC_LEN variable.

Previously, the maxlength attribute on the <input> fields in settings_sync.html were set with inputElement.maxlength = <length>, however this did not seem to actually modify the maxlength attribute as seen in the screenshot (also I couldn't type any more characters than the previous maxlength setting):

As seen, modifying element.maxlength does actually modify the variable, but it does not modify the maxlength attribute weirdly. Using element.setAttribute("maxlength", X) was the fix.

In this PR I've modified the code to implement a function to use this JS line instead of the one previously used.

[WouterGritter]

Tagging you @softhack007 as you're aware of the context of the previous PR.

[softhack007]

Tagging you @softhack007 as you're aware of the context of the previous PR.

Hi,

sorry HTML/JS is not my area.

[blazoncek]

If I was doing something like general method for modifying any attribute, I would have done it something like this:

function upAttr(o,a,v)
{
    d.Sf[o].setAttribute(a,v);
}

settingsScript.printf_P(PSTR("upAttr('MD','maxlength',%d);upAttr('MG','maxlength',%d);upAttr('MS','maxlength',%d);"),
   MQTT_MAX_TOPIC_LEN, MQTT_MAX_TOPIC_LEN, MQTT_MAX_SERVER_LEN);

But particular case is only the issue of missing uppercase letter. Instead of maxlength JavaScript access needs property called maxLength.

So, according to W3C Schools, the solution with least change is:

settingsScript.printf_P(PSTR("d.Sf.MD.maxLength=%d;d.Sf.MG.maxLength=%d;d.Sf.MS.maxLength=%d;"),
              MQTT_MAX_TOPIC_LEN, MQTT_MAX_TOPIC_LEN, MQTT_MAX_SERVER_LEN);

[WouterGritter]

Damn, great catch. I agree with making the least amount of changes required. Will replace maxlength with maxLength like you proposed (tested it and it works).

[WouterGritter]

I think we can merge this now.