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Simple JS equivalent of the Python set() constructor (without the methods)
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/** | |
* Simple JS equivalent of the Python set() constructor (without the methods) | |
* @requires shim: Array.prototype.indexOf | |
* @param {array} arr The array to turn into a set | |
* @example | |
* var mySet = set(['red', 'yellow', 'black', 'yellow']); | |
* mySet.length; // 3 | |
* JSON.stringify(mySet); // ["red","yellow","black"] | |
* @see For a fuller version, see {@link https://npmjs.org/package/set} | |
*/ | |
function set (arr) { | |
return arr.reduce(function (a, val) { | |
if (a.indexOf(val) === -1) { | |
a.push(val); | |
} | |
return a; | |
}, []); | |
} |
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Came here after googling "python set in javascript".
For other readers like me, note that this isn't equivalent to Python's set() performance-wise. Python's set uses a hashtable to check if values have been encountered before, whereas this uses
Array#indexOf
.If we use an object instead of an array in
reduce
we can get there performance-wise: fork of this gist