startsWith.js
 1  var baseClamp = require('./_baseClamp'),
 2      baseToString = require('./_baseToString'),
 3      toInteger = require('./toInteger'),
 4      toString = require('./toString');
 5  
 6  /**
 7   * Checks if `string` starts with the given target string.
 8   *
 9   * @static
10   * @memberOf _
11   * @since 3.0.0
12   * @category String
13   * @param {string} [string=''] The string to inspect.
14   * @param {string} [target] The string to search for.
15   * @param {number} [position=0] The position to search from.
16   * @returns {boolean} Returns `true` if `string` starts with `target`,
17   *  else `false`.
18   * @example
19   *
20   * _.startsWith('abc', 'a');
21   * // => true
22   *
23   * _.startsWith('abc', 'b');
24   * // => false
25   *
26   * _.startsWith('abc', 'b', 1);
27   * // => true
28   */
29  function startsWith(string, target, position) {
30    string = toString(string);
31    position = position == null
32      ? 0
33      : baseClamp(toInteger(position), 0, string.length);
34  
35    target = baseToString(target);
36    return string.slice(position, position + target.length) == target;
37  }
38  
39  module.exports = startsWith;