Javascript – print all methods of an object

To print all methods of an object, we can use Object.getOwnPropertyNames and check if the corresponding value is a function. The Object.getOwnPropertyNames() method returns an array of all properties (enumerable or not) found directly upon a given object. Here are some code snippets.

Print all methods of Array

var classobj = Array;
console.log(Object.getOwnPropertyNames(classobj).filter(function (x) {
  return typeof classobj[x] === 'function'
}));
[ 'isArray', 'from', 'of', 'observe', 'unobserve' ]
Env: node version v5.12.0

Print all methods of Array.prototype

var classobj = Array.prototype;
console.log(Object.getOwnPropertyNames(classobj).filter(function (x) {
  return typeof classobj[x] === 'function'
}));
[ 'constructor',
  'toString',
  'toLocaleString',
  'join',
  'pop',
  'push',
  'concat',
  'reverse',
  'shift',
  'unshift',
  'slice',
  'splice',
  'sort',
  'filter',
  'forEach',
  'some',
  'every',
  'map',
  'indexOf',
  'lastIndexOf',
  'reduce',
  'reduceRight',
  'entries',
  'keys',
  'copyWithin',
  'find',
  'findIndex',
  'fill' ]
Env: node version v5.12.0

Note that Array.prototype properties are different from Array properties.

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