message: Fixed: Convert to number.
diff: @@ -9,7 +9,7 @@ export default function() {
  if (number === '-') {
  number = 0;
  }
  - this.opts.onchange(number + (this.opts.step || 1) );
  + this.opts.onchange(Number(number) + (this.opts.step || 1) );
  };
  this.handleDecreaseButtonPat = () => {
  @@ -21,7 +21,7 @@ export default function() {
  if (number === '-') {
  number = 0;
  }
  - this.opts.onchange(number - (this.opts.step || 1) );
  + this.opts.onchange(Number(number) - (this.opts.step || 1) );
  };
  this.handleKeyDown = (e) => {
  @@ -44,6 +44,7 @@ export default function() {
  this.handleInputInput = e => {
  e.preventUpdate = true;
  let newText = e.target.value.replace(/[^-^0-9]/g, '');// eslint-disable-line no-irregular-whitespace
  + console.log(newText);
  if(!newText.length || newText.match(/^([-]?[1-9][0-9]*?|-|0)$/)) {
  this.opts.onchange(newText);
  }else {
  