Disable backspace navigation when textarea has content react mixin

backspace_nav_handler_mixins.js

module.exports = {
  disableBackspaceNavEvent: function(event) {
    if (event.keyCode == 8) {
      if (event.target.type && event.target.type.match(/text/)) {
        return true
      } else {
        event.preventDefault()
      }
    }
  },
  disableBackspaceNav: function() {
    window.removeEventListener('keydown', this.disableBackspaceNavEvent)
    window.addEventListener('keydown', this.disableBackspaceNavEvent)
  },

  enableBackspaceNav: function() {
    window.removeEventListener('keydown',this.disableBackspaceNavEvent)
  },

  componentWillUnmount: function() {
    this.enableBackspaceNav()
  }
}

module_with_textarea.jsx

var React = require('react')
var BackspaceNavHandler = require('backspace_nav_handler_mixins')

module.exports = React.createClass({

  mixins: [ BackspaceNavHandler ],
  
  render: function() {
    return (
      <textarea onBlur={this.disableBackspaceNav} onFocus={this.enableBackspaceNav} />      
    )
  }

})

Ran into a situation where the component was visible but user brought focus to an entirely unrelated field on the page and of course backspace wouldn't work. This should fix that but will probably fail in contenteditables. Needs a good "is DOM element and input" test.