@material-ui/core/es/utils/helpers.js

React components that implement Google's Material Design.

import warning from 'warning';
export function capitalize(string) {
  if (process.env.NODE_ENV !== 'production' && typeof string !== 'string') {
    throw new Error('Material-UI: capitalize(string) expects a string argument.');
  }

  return string.charAt(0).toUpperCase() + string.slice(1);
}
export function contains(obj, pred) {
  return Object.keys(pred).every(key => {
    return obj.hasOwnProperty(key) && obj[key] === pred[key];
  });
}
export function findIndex(arr, pred) {
  const predType = typeof pred;

  for (let i = 0; i < arr.length; i += 1) {
    if (predType === 'function' && !!pred(arr[i], i, arr) === true) {
      return i;
    }

    if (predType === 'object' && contains(arr[i], pred)) {
      return i;
    }

    if (['string', 'number', 'boolean'].indexOf(predType) !== -1) {
      return arr.indexOf(pred);
    }
  }

  return -1;
}
export function find(arr, pred) {
  const index = findIndex(arr, pred);
  return index > -1 ? arr[index] : undefined;
}
/**
 * Safe chained function
 *
 * Will only create a new function if needed,
 * otherwise will pass back existing functions or null.
 *
 * @param {function} functions to chain
 * @returns {function|null}
 */

export function createChainedFunction(...funcs) {
  return funcs.reduce((acc, func) => {
    if (func == null) {
      return acc;
    }

    process.env.NODE_ENV !== "production" ? warning(typeof func === 'function', 'Material-UI: invalid Argument Type, must only provide functions, undefined, or null.') : void 0;
    return function chainedFunction(...args) {
      acc.apply(this, args);
      func.apply(this, args);
    };
  }, () => {});
}