Can I update a component s props in React js

Question

After starting to work with React js  it seems like props are intended to be static  passed in from the parent component   while state changes based upon events   However  I noticed in the docs a reference to componentWillReceiveProps  which specifically includes this example     componentWillReceiveProps  function nextProps       this setState        likesIncreasing  nextProps likeCount  gt  this props likeCount                This seems to imply that the properties CAN change on a component based upon the comparison of nextProps to this props   What am I missing   How do props change  or am I mistaken about where this gets called

User · Answer

Props can change when a component s parent renders the component again with different properties  I think this is mostly an optimization so that no new component needs to be instantiated

User · Answer

if you use recompose  use mapProps to make new props derived from incoming props      Edit for example   import   compose  mapProps   from  recompose    const SomeComponent      url  onComplete      gt       url          lt View   gt        null     export default compose    mapProps    url  storeUrl  history     props      gt            props      onClose       gt          history goBack               url  url    storeUrl           SomeComponent

User · Answer

PROPS     A React component should use props to store information that can be   changed  but can only be changed by a different component    STATE     A React component should use state to store information that the   component itself can change    A good example is already provided by Val  ry

User · Answer

Trick to update props if they are array    import React    Component   from  react   import     AppRegistry    StyleSheet    Text    View    Button   from  react-native    class Counter extends Component     constructor props        super props         this state             count  this props count                 increment        console log  this props count        console log this props count       let count   this state count     count push  new element        this setState   count  count         render          return          lt View style  styles container  gt           lt Text gt   this state count length   lt  Text gt           lt Button           onPress  this increment bind this             title    Increase              gt         lt  View gt                Counter defaultProps      count        export default Counter const styles   StyleSheet create     container        flex  1      justifyContent   center       alignItems   center       backgroundColor    F5FCFF          welcome        fontSize  20      textAlign   center       margin  10         instructions        textAlign   center       color    333333       marginBottom  5

User · Answer

Much has changed with hooks  e g  componentWillReceiveProps turned into useEffect useRef  as shown in this other SO answer   but Props are still Read-Only  so only the caller method should update it

User · Answer

A component cannot update its own props unless they are arrays or objects  having a component update its own props even if possible is an anti-pattern   but can update its state and the props of its children   For instance  a Dashboard has a speed field in its state  and passes it to a Gauge child thats displays this speed  Its render method is just return  lt Gauge speed  this state speed    gt   When the Dashboard calls this setState  speed  this state speed   1    the Gauge is re-rendered with the new value for speed   Just before this happens  Gauge s componentWillReceiveProps is called  so that the Gauge has a chance to compare the new value to the old one

[javascript] Can I update a component's props in React.js?

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