react-render-if

A decorator that can take any number of functions as predicates. The predicates are called with the current instance of the component as the first parameter. If the return value of all the params is truthy only then the component is rendered.

When to render a component is primarly a property of the component. We often implement this behaviour in the render() function which mixes up with its primary responsiblity of — how to render. This makes the code difficult to read at the same time the logic becomes local to that particular render function and thus becomes non-reusable. This decorator helps alleviate that and follow DRY

Installation

npm i react-render-if --save

Before

class UserList extends Component {
  componentWillMount () {
    this.setState({list: []})
    
    setInterval(x => {
      const list = this.state.list.slice()
      list.push(new Date())
      this.setState({list})
    }, 1000)
    
  }
  render () {
    // Complex logic inside the render function about "when to render" the component.
    // Interferes with the "how to render" which should be it primary responsibility.
    if(this.state === null || this.state.list.length === 0){
      return null
    }
  
    return (
      <ul>
        {this.state.list.map((x, i) => <li key={i}>{x}</li>)}
      </ul>
    )
  }
}

Usage

import {renderIf} from 'react-render-if'
import {Component} from 'react'

// Takes in n number of predicates
@renderIf(  
  x => x.state !== null, 
  x => x.state.list.length > 0
)
class UserList extends Component {
  componentWillMount () {
    this.setState({list: []})
    
    setInterval(x => {
      const list = this.state.list.slice()
      list.push(new Date())
      this.setState({list})
    }, 1000)
    
  }
  render () {
    return (
      <ul>
        {this.state.list.map((x, i) => <li key={i}>{x}</li>)}
      </ul>
    )
  }
}

Even Better

import {renderIf, itsGT} from 'react-render-if'
import {Component} from 'react'
 
// itsGT() is a helper that makes sure that the component is only rendered if state.list.length is greater than 0
@renderIf(itsGT('state.list.length', 0))
class UserList extends Component {
  ...
}

API Helpers

Some useful helper functions are added as a part of this library so that you don't have to write anon arrow functions.

• itHas(<path>): renders if the path exists on a component. Eg. 'state.list.length'

• itsTrue(<path>): renders if true is set at the path.

• itsFalse(<path>): renders if false is set at the path.

• itsOk(<path>): renders if path has a truthy value.

• itsNotOk(<path>): renders if path has a falsey value.

• itsGT(<path>, <value>): renders if the value at path is greater than the value passed as the second param. Other versions of this comparisons are — itsGTE, itsLTE & itsLT. All of which take in as the first param and as the second.

• itsEqual(<path>, <value>): renders if the value at the given path is equal to what is being passed as the second param.

• itsNotEqual(<path>, <value>): renders if the value at the given path is NOT equal to what is being passed as the second param.

Uses lodash custom build

lodash include=has,get,curry,toArray -d