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JavaScript: Print all the methods in an JavaScript object

JavaScript Object: Exercise-11 with Solution

Write a JavaScript function to print all the methods in an JavaScript object.
Test Data:
console.log(all_properties(Array));
["length", "name", "arguments", "caller", "prototype", "isArray", "observe", "unobserve"]

Sample Solution: -

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript function to display all methods in a object.</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function FindAllMethods(obj) {
    return Object.getOwnPropertyNames(obj).filter(function(property) {
        return typeof obj[property] == "function";
    });
}
//above code finds methods only
//Following code finds both properties and methods 
console.log(FindAllMethods(Math));
console.log(FindAllMethods(Array));
function all_properties(obj) 
{
 return Object.getOwnPropertyNames(obj);
}

console.log(all_properties(Math));

console.log(all_properties(Array));

Sample Output:

["abs", "acos", "acosh", "asin", "asinh", "atan", "atanh", "atan2", "ceil", "cbrt", "expm1", "clz32", "cos", "cosh", "exp", "floor", "fround", "hypot", "imul", "log", "log1p", "log2", "log10", "max", "min", "pow", "random", "round", "sign", "sin", "sinh", "sqrt", "tan", "tanh", "trunc"]
["isArray", "from", "of"]
["abs", "acos", "acosh", "asin", "asinh", "atan", "atanh", "atan2", "ceil", "cbrt", "expm1", "clz32", "cos", "cosh", "exp", "floor", "fround", "hypot", "imul", "log", "log1p", "log2", "log10", "max", "min", "pow", "random", "round", "sign", "sin", "sinh", "sqrt", "tan", "tanh", "trunc", "E", "LN10", "LN2", "LOG10E", "LOG2E", "PI", "SQRT1_2", "SQRT2"]
["length", "name", "prototype", "isArray", "from", "of"]

Flowchart:

Flowchart: JavaScript - Print all the methods in an JavaScript object.

Live Demo:

Click on the Codepen logo at the top right corner of the code snippet below to view the output.

See the Pen javascript-object-exercise-11 by w3resource (@w3resource) on CodePen.


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JavaScript: Tips of the Day

How to remove a specific item from an array?

Find the index of the array element you want to remove using indexOf, and then remove that index with splice.

The splice() method changes the contents of an array by removing existing elements and/or adding new elements.

const array = [2, 5, 9];

console.log(array);

const index = array.indexOf(5);
if (index > -1) {
  array.splice(index, 1);
}

// array = [2, 9]
console.log(array);

The second parameter of splice is the number of elements to remove. Note that splice modifies the array in place and returns a new array containing the elements that have been removed.

For the reason of completeness, here are functions. The first function removes only a single occurrence (i.e. removing the first match of 5 from [2,5,9,1,5,8,5]), while the second function removes all occurrences:

function removeItemOnce(arr, value) {
  var index = arr.indexOf(value);
  if (index > -1) {
    arr.splice(index, 1);
  }
  return arr;
}

function removeItemAll(arr, value) {
  var i = 0;
  while (i < arr.length) {
    if (arr[i] === value) {
      arr.splice(i, 1);
    } else {
      ++i;
    }
  }
  return arr;
}
//Usage
console.log(removeItemOnce([2,5,9,1,5,8,5], 5))
console.log(removeItemAll([2,5,9,1,5,8,5], 5))

Ref: https://bit.ly/2N9nKRp