Underscore 源码解读 - Collection Functions

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Underscore - Collection Functions

contains

别名：includes, include
语法：_.contains( list, value [ , fromIndex ] )
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// Determine if the array or object contains a given item (using `===`).
// Aliased as `includes` and `include`.
_.contains = _.includes = _.include = function(obj, item, fromIndex, guard) {
  if (!isArrayLike(obj)) obj = _.values(obj);
  if (typeof fromIndex != 'number' || guard) fromIndex = 0;
  return _.indexOf(obj, item, fromIndex) >= 0;
};