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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

instance

class Calc {
	constructor() {
		this.count = 0 
	}

	increase() {
		this.count ++
	}
}

const calc = new Calc()
new Calc().increase()

console.log(calc.count)

We set the variable calc equal to a new instance of the Calc class. Then, we instantiate a new instance of Calc, and invoke the increase method on this instance. Since the count property is within the constructor of the Calc class, the count property is not shared on the prototype of Calc. This means that the value of count has not been updated for the instance calc points to, count is still 0.

Ref: https://bit.ly/2Hcpkm6