padStart.js

var createPadding = require('./_createPadding'),
    stringSize = require('./_stringSize'),
    toInteger = require('./toInteger'),
    toString = require('./toString');

/**
 * Pads `string` on the left side if it's shorter than `length`. Padding
 * characters are truncated if they exceed `length`.
 *
 * @static
 * @memberOf _
 * @since 4.0.0
 * @category String
 * @param {string} [string=''] The string to pad.
 * @param {number} [length=0] The padding length.
 * @param {string} [chars=' '] The string used as padding.
 * @returns {string} Returns the padded string.
 * @example
 *
 * _.padStart('abc', 6);
 * // => '   abc'
 *
 * _.padStart('abc', 6, '_-');
 * // => '_-_abc'
 *
 * _.padStart('abc', 3);
 * // => 'abc'
 */
function padStart(string, length, chars) {
  string = toString(string);
  length = toInteger(length);

  var strLength = length ? stringSize(string) : 0;
  return (length && strLength < length)
    ? (createPadding(length - strLength, chars) + string)
    : string;
}

module.exports = padStart;