Add getInputArrayFromProps util, use it to initialize this.state.input

also, add getValueFromProps util to handle props.forceUppercase and null | undefined

src/ReactCodeInput.js

@@ -7,7 +7,7 @@
 import React, { Component } from 'react';
 import PropTypes from 'prop-types';
 import classNames from 'classnames';
-import { uuidv4 } from './utils';
+import { getInputArrayFromProps, getValueFromProps, uuidv4 } from './utils';
 
 const BACKSPACE_KEY = 8;
 const LEFT_ARROW_KEY = 37;
@@ -32,23 +32,11 @@ class ReactCodeInput extends Component {
   constructor(props) {
     super(props);
 
-    const { fields, forceUppercase } = props;
-    let value = props.value || '';
-
-    if (forceUppercase) {
-      value = value.toUpperCase();
-    }
-
     this.state = {
-      value,
-      input: [],
+      input: getInputArrayFromProps(props),
+      value: getValueFromProps(props),
     };
 
-    for (let i = 0; i < Number(fields) && i < 32; i += 1) {
-      const value = this.state.value[i] || '';
-      this.state.input.push(value);
-    }
-
     this.textInput = [];
 
     this.uuid = uuidv4();

src/utils.js

@@ -3,4 +3,15 @@ export const uuidv4 = () => {
         let r = Math.random() * 16 | 0, v = c === 'x' ? r : (r & 0x3 | 0x8);
         return v.toString(16);
     });
-};
+};
+
+export const getValueFromProps = ({ forceUppercase, value }) => {
+  value = value == null ? '' : value;
+  return forceUppercase ? value.toUpperCase() : value;
+};
+
+export const getInputArrayFromProps = (props) => {
+  const fields = Math.min(32, props.fields);
+  const value = getValueFromProps(props);
+  return Array.from(Array(fields)).map((_, index) => value[index] || '');
+};