[SalesForce] In lightning components, How to check if input value really changed

My goal is to check if the user really changed the value in the input field.

In visualforce, I do this by storing the old value in HTML5 data attributes and onchange event compare the old value with the new value to see if it really changed:

<apex:inputField value="{!oppObj.field1__c}"
                 html-data-oldValue="{!oppObj.field1__c}">
</apex:inputField

But I am confused as how to do the same in lightning components as these are not supporting html5 data attributes. I have code something like this and it is not taking html5 data attributes. 

<ui:inputNumber aura:id="someFld" 
                class="slds-input" 
                value="{!oppObj.field1__c}"
                change="{!c.fieldChanged}">
</ui:inputNumber>

Any help on this?

EDIT:

I have ui:inputNumber inside the aura:iteration tag, so it is like this:

<aura:iteration items="{!v.oppList}"
                var="oppObj"
                indexVar="i">
    <ui:inputNumber aura:id="{!i + '_someFld'}" 
                    class="slds-input" 
                    value="{!oppObj.field1__c}">
    </ui:inputNumber>
</aura:iteration>

As suggested, I am trying to define <aura:handler name="change"../> inside aura:iteration but it throws this error :

Failed to save undefined: markup://c:TestComponent:231,67:
Invalid attribute "name": Source

Best Answer

You could use a handler for that.

Add this to your component:

<aura:handler name="change" value="{!v.value}" action="{!c.valueChanged}"/>

v.value = aura:attribute

c.valueChanged = method in your lightning controller

Then your ui:input would be like so: 

<ui:inputNumber aura:id="someFld" 
            class="slds-input" 
            value="{!v.value}"
            change="{c.valueChanged}">
</ui:inputNumber>

Example here.

Related Topic