voca/first.js

The ultimate JavaScript string library

'use strict';

var is_nil = require('./internal/is_nil.js');
require('./is_string.js');
var coerce_to_string = require('./internal/coerce_to_string.js');
var to_integer = require('./internal/to_integer.js');

/**
 * Extracts the first `length` characters from `subject`.
 *
 * @function first
 * @static
 * @since 1.0.0
 * @memberOf Chop
 * @param  {string} [subject=''] The string to extract from.
 * @param  {int}    [length=1]   The number of characters to extract.
 * @return {string}              Returns the first characters string.
 * @example
 * v.first('helicopter');
 * // => 'h'
 *
 * v.first('vehicle', 2);
 * // => 've'
 *
 * v.first('car', 5);
 * // => 'car'
 */

function first(subject, length) {
  var subjectString = coerce_to_string.coerceToString(subject);
  var lengthInt = is_nil.isNil(length) ? 1 : to_integer.clipNumber(to_integer.toInteger(length), 0, to_integer.MAX_SAFE_INTEGER);

  if (subjectString.length <= lengthInt) {
    return subjectString;
  }

  return subjectString.substr(0, lengthInt);
}

module.exports = first;