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console.log('21/10/2020'.match(/(0[1-9]|1[0-9]|2[0-9]|3[0-])\/(0[1-9]|1[0-2])\/([1|2][0-9][0-9][0-9])/g))
console.log('21/10/2020'.match(/(0[1-9]|1[0-9]|2[0-9]|3[0-])\/(0[1-9]|1[0-2])\/([1|2][0-9][0-9][0-9])/g))