Methods inside of functional components










0















I'm experiencing a strange issue where the onPress function of a functional child component is triggered whenever the component is rendered.



Relevant parent code which renders the child component from a list of dates. I was also having issues with array.map if the component was a class component, but that's a separate issue.



return list_items.map(data => 
<ChildComponent
key=data.day
props=data
/>);


And the child component:



const ChildComponent = ( props ) => {
let date = props.date;
const someFunction = () =>
console.log(date)

return (
<Text><Icon name="angle-right" onPress=someFunction()/></Text>
)


And what I get from the console upon rendering the relevant scene:




2018-11-11



2018-11-12



2018-11-13



2018-11-14



2018-11-15



2018-11-16




Pressing the icon does nothing, yet it seems to run the function as if it was a lifecycle component. I've also moved the function into the parent component and passed it to the child as recommended per Guruparan Giritharan, and it still executes on render.



return list_items.map(data => 
<ChildComponent
key=data.day
props=data
someFunction=this.someFunction // function now within parent component
/>);


And the updated child:



const ChildComponent = ( props, someFunction ) => 
return (
<Text>
<Icon name="angle-right" onPress=someFunction(props.date)/>
</Text>
)










share|improve this question




























    0















    I'm experiencing a strange issue where the onPress function of a functional child component is triggered whenever the component is rendered.



    Relevant parent code which renders the child component from a list of dates. I was also having issues with array.map if the component was a class component, but that's a separate issue.



    return list_items.map(data => 
    <ChildComponent
    key=data.day
    props=data
    />);


    And the child component:



    const ChildComponent = ( props ) => {
    let date = props.date;
    const someFunction = () =>
    console.log(date)

    return (
    <Text><Icon name="angle-right" onPress=someFunction()/></Text>
    )


    And what I get from the console upon rendering the relevant scene:




    2018-11-11



    2018-11-12



    2018-11-13



    2018-11-14



    2018-11-15



    2018-11-16




    Pressing the icon does nothing, yet it seems to run the function as if it was a lifecycle component. I've also moved the function into the parent component and passed it to the child as recommended per Guruparan Giritharan, and it still executes on render.



    return list_items.map(data => 
    <ChildComponent
    key=data.day
    props=data
    someFunction=this.someFunction // function now within parent component
    />);


    And the updated child:



    const ChildComponent = ( props, someFunction ) => 
    return (
    <Text>
    <Icon name="angle-right" onPress=someFunction(props.date)/>
    </Text>
    )










    share|improve this question


























      0












      0








      0








      I'm experiencing a strange issue where the onPress function of a functional child component is triggered whenever the component is rendered.



      Relevant parent code which renders the child component from a list of dates. I was also having issues with array.map if the component was a class component, but that's a separate issue.



      return list_items.map(data => 
      <ChildComponent
      key=data.day
      props=data
      />);


      And the child component:



      const ChildComponent = ( props ) => {
      let date = props.date;
      const someFunction = () =>
      console.log(date)

      return (
      <Text><Icon name="angle-right" onPress=someFunction()/></Text>
      )


      And what I get from the console upon rendering the relevant scene:




      2018-11-11



      2018-11-12



      2018-11-13



      2018-11-14



      2018-11-15



      2018-11-16




      Pressing the icon does nothing, yet it seems to run the function as if it was a lifecycle component. I've also moved the function into the parent component and passed it to the child as recommended per Guruparan Giritharan, and it still executes on render.



      return list_items.map(data => 
      <ChildComponent
      key=data.day
      props=data
      someFunction=this.someFunction // function now within parent component
      />);


      And the updated child:



      const ChildComponent = ( props, someFunction ) => 
      return (
      <Text>
      <Icon name="angle-right" onPress=someFunction(props.date)/>
      </Text>
      )










      share|improve this question
















      I'm experiencing a strange issue where the onPress function of a functional child component is triggered whenever the component is rendered.



      Relevant parent code which renders the child component from a list of dates. I was also having issues with array.map if the component was a class component, but that's a separate issue.



      return list_items.map(data => 
      <ChildComponent
      key=data.day
      props=data
      />);


      And the child component:



      const ChildComponent = ( props ) => {
      let date = props.date;
      const someFunction = () =>
      console.log(date)

      return (
      <Text><Icon name="angle-right" onPress=someFunction()/></Text>
      )


      And what I get from the console upon rendering the relevant scene:




      2018-11-11



      2018-11-12



      2018-11-13



      2018-11-14



      2018-11-15



      2018-11-16




      Pressing the icon does nothing, yet it seems to run the function as if it was a lifecycle component. I've also moved the function into the parent component and passed it to the child as recommended per Guruparan Giritharan, and it still executes on render.



      return list_items.map(data => 
      <ChildComponent
      key=data.day
      props=data
      someFunction=this.someFunction // function now within parent component
      />);


      And the updated child:



      const ChildComponent = ( props, someFunction ) => 
      return (
      <Text>
      <Icon name="angle-right" onPress=someFunction(props.date)/>
      </Text>
      )







      react-native jsx






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 13 '18 at 16:50







      NathanL

















      asked Nov 13 '18 at 5:03









      NathanLNathanL

      769




      769






















          1 Answer
          1






          active

          oldest

          votes


















          1














          Change to



          <Text><Icon name="angle-right" onPress=someFunction/></Text>


          You are calling the function there itself instead of passing the reference. So the function is called inside each render instead of onPress.






          share|improve this answer























          • I changed it so that the function exists inside of the parent component and is being called by the child component, yet no change.

            – NathanL
            Nov 13 '18 at 16:44






          • 1





            Do you pass the function of parent component as a prop ?, do you get the console log when you press the icon ?

            – Guruparan Giritharan
            Nov 13 '18 at 16:49






          • 1





            you are calling the function on render onPress=someFunction(props.date) thats the problem it should be a reference onPress=this.props.someFunction

            – Guruparan Giritharan
            Nov 13 '18 at 17:00






          • 1





            if you need to use someFunction in your onPress along with date the way will be <Icon name="angle-right" onPress=()=>someFunction(props.date)/>

            – Guruparan Giritharan
            Nov 13 '18 at 17:11






          • 1





            I changed it back to a class-based component and it worked.

            – NathanL
            Nov 13 '18 at 17:21










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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          1














          Change to



          <Text><Icon name="angle-right" onPress=someFunction/></Text>


          You are calling the function there itself instead of passing the reference. So the function is called inside each render instead of onPress.






          share|improve this answer























          • I changed it so that the function exists inside of the parent component and is being called by the child component, yet no change.

            – NathanL
            Nov 13 '18 at 16:44






          • 1





            Do you pass the function of parent component as a prop ?, do you get the console log when you press the icon ?

            – Guruparan Giritharan
            Nov 13 '18 at 16:49






          • 1





            you are calling the function on render onPress=someFunction(props.date) thats the problem it should be a reference onPress=this.props.someFunction

            – Guruparan Giritharan
            Nov 13 '18 at 17:00






          • 1





            if you need to use someFunction in your onPress along with date the way will be <Icon name="angle-right" onPress=()=>someFunction(props.date)/>

            – Guruparan Giritharan
            Nov 13 '18 at 17:11






          • 1





            I changed it back to a class-based component and it worked.

            – NathanL
            Nov 13 '18 at 17:21















          1














          Change to



          <Text><Icon name="angle-right" onPress=someFunction/></Text>


          You are calling the function there itself instead of passing the reference. So the function is called inside each render instead of onPress.






          share|improve this answer























          • I changed it so that the function exists inside of the parent component and is being called by the child component, yet no change.

            – NathanL
            Nov 13 '18 at 16:44






          • 1





            Do you pass the function of parent component as a prop ?, do you get the console log when you press the icon ?

            – Guruparan Giritharan
            Nov 13 '18 at 16:49






          • 1





            you are calling the function on render onPress=someFunction(props.date) thats the problem it should be a reference onPress=this.props.someFunction

            – Guruparan Giritharan
            Nov 13 '18 at 17:00






          • 1





            if you need to use someFunction in your onPress along with date the way will be <Icon name="angle-right" onPress=()=>someFunction(props.date)/>

            – Guruparan Giritharan
            Nov 13 '18 at 17:11






          • 1





            I changed it back to a class-based component and it worked.

            – NathanL
            Nov 13 '18 at 17:21













          1












          1








          1







          Change to



          <Text><Icon name="angle-right" onPress=someFunction/></Text>


          You are calling the function there itself instead of passing the reference. So the function is called inside each render instead of onPress.






          share|improve this answer













          Change to



          <Text><Icon name="angle-right" onPress=someFunction/></Text>


          You are calling the function there itself instead of passing the reference. So the function is called inside each render instead of onPress.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 13 '18 at 6:32









          Guruparan GiritharanGuruparan Giritharan

          4751618




          4751618












          • I changed it so that the function exists inside of the parent component and is being called by the child component, yet no change.

            – NathanL
            Nov 13 '18 at 16:44






          • 1





            Do you pass the function of parent component as a prop ?, do you get the console log when you press the icon ?

            – Guruparan Giritharan
            Nov 13 '18 at 16:49






          • 1





            you are calling the function on render onPress=someFunction(props.date) thats the problem it should be a reference onPress=this.props.someFunction

            – Guruparan Giritharan
            Nov 13 '18 at 17:00






          • 1





            if you need to use someFunction in your onPress along with date the way will be <Icon name="angle-right" onPress=()=>someFunction(props.date)/>

            – Guruparan Giritharan
            Nov 13 '18 at 17:11






          • 1





            I changed it back to a class-based component and it worked.

            – NathanL
            Nov 13 '18 at 17:21

















          • I changed it so that the function exists inside of the parent component and is being called by the child component, yet no change.

            – NathanL
            Nov 13 '18 at 16:44






          • 1





            Do you pass the function of parent component as a prop ?, do you get the console log when you press the icon ?

            – Guruparan Giritharan
            Nov 13 '18 at 16:49






          • 1





            you are calling the function on render onPress=someFunction(props.date) thats the problem it should be a reference onPress=this.props.someFunction

            – Guruparan Giritharan
            Nov 13 '18 at 17:00






          • 1





            if you need to use someFunction in your onPress along with date the way will be <Icon name="angle-right" onPress=()=>someFunction(props.date)/>

            – Guruparan Giritharan
            Nov 13 '18 at 17:11






          • 1





            I changed it back to a class-based component and it worked.

            – NathanL
            Nov 13 '18 at 17:21
















          I changed it so that the function exists inside of the parent component and is being called by the child component, yet no change.

          – NathanL
          Nov 13 '18 at 16:44





          I changed it so that the function exists inside of the parent component and is being called by the child component, yet no change.

          – NathanL
          Nov 13 '18 at 16:44




          1




          1





          Do you pass the function of parent component as a prop ?, do you get the console log when you press the icon ?

          – Guruparan Giritharan
          Nov 13 '18 at 16:49





          Do you pass the function of parent component as a prop ?, do you get the console log when you press the icon ?

          – Guruparan Giritharan
          Nov 13 '18 at 16:49




          1




          1





          you are calling the function on render onPress=someFunction(props.date) thats the problem it should be a reference onPress=this.props.someFunction

          – Guruparan Giritharan
          Nov 13 '18 at 17:00





          you are calling the function on render onPress=someFunction(props.date) thats the problem it should be a reference onPress=this.props.someFunction

          – Guruparan Giritharan
          Nov 13 '18 at 17:00




          1




          1





          if you need to use someFunction in your onPress along with date the way will be <Icon name="angle-right" onPress=()=>someFunction(props.date)/>

          – Guruparan Giritharan
          Nov 13 '18 at 17:11





          if you need to use someFunction in your onPress along with date the way will be <Icon name="angle-right" onPress=()=>someFunction(props.date)/>

          – Guruparan Giritharan
          Nov 13 '18 at 17:11




          1




          1





          I changed it back to a class-based component and it worked.

          – NathanL
          Nov 13 '18 at 17:21





          I changed it back to a class-based component and it worked.

          – NathanL
          Nov 13 '18 at 17:21

















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