code: function each( source, iterator ) {
          if ( isArray( source ) ) {
              for ( var i = 0, len = source.length; i < len; i++ ) {
                  if ( iterator( source[ i ], i ) === false ) {
                      break;
                  }
              }
          }
      }
docs: 循环遍历数组集合
  
  @ignore
  @param {Array} source 数组源
  @param {function(Array,Number):boolean} iterator 遍历函数