---
id: props-in-getInitialState-as-anti-pattern
title: Props in getInitialState Is an Anti-Pattern
layout: tips
permalink: props-in-getInitialState-as-anti-pattern.html
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---
> Note:
>
> This isn't really a React-specific tip, as such anti-patterns often occur in code in general; in this case, React simply points them out more clearly.
Using props, passed down from parent, to generate state in `getInitialState` often leads to duplication of "source of truth", i.e. where the real data is. Whenever possible, compute values on-the-fly to ensure that they don't get out of sync later on and cause maintenance trouble.
**Bad example:**
```js
/** @jsx React.DOM */
var MessageBox = React.createClass({
getInitialState: function() {
return {nameWithQualifier: "Mr. " + this.props.name};
},
render: function() {
return < div > {this.state.nameWithQualifier}< / div > ;
}
});
React.renderComponent(< MessageBox name = "Rogers" / > , mountNode);
```
Better:
```js
/** @jsx React.DOM */
var MessageBox = React.createClass({
render: function() {
return < div > {"Mr. " + this.props.name}< / div > ;
}
});
React.renderComponent(< MessageBox name = "Rogers" / > , mountNode);
```
(For more complex logic, simply isolate the computation in a method.)
However, it's **not** an anti-pattern if you make it clear that synchronization's not the goal here:
```js
/** @jsx React.DOM */
var Counter = React.createClass({
getInitialState: function() {
// naming it initialX clearly indicates that the only purpose
// of the passed down prop is to initialize something internally
return {count: this.props.initialCount};
},
handleClick: function() {
this.setState({count: this.state.count + 1});
},
render: function() {
return < div onClick = {this.handleClick} > {this.state.count}< / div > ;
}
});
React.renderComponent(< Counter initialCount = {7}/ > , mountNode);
```
