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JavaScript: Check whether an 'input' is a string or not

JavaScript String: Exercise-1 with Solution

Write a JavaScript function to check whether an 'input' is a string or not.

Test Data:
console.log(is_string('w3resource'));
true
console.log(is_string([1, 2, 4, 0]));
false

Pictorial Presentation:

JavaScript: Check whether an 'input' is a string or not

Sample Solution:-

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Check whether an input is a string or not</title>
</head>
<body>
</body>
</html>

JavaScript Code:

is_string = function(input) {
  if (Object.prototype.toString.call(input) === '[object String]')
    return true;
  else
    return false;   
    };
console.log(is_string('w3resource'));
console.log(is_string([1, 2, 4, 0]));

Sample Output:

true
false

Flowchart:

Flowchart: JavaScript- Check whether an 'input' is a string or not

Live Demo:

See the Pen JavaScript Print an integer with commas as thousands separators - string-ex-1 by w3resource (@w3resource) on CodePen.


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JavaScript: Tips of the Day

var functionName = function() {} vs function functionName() {}

The difference is that functionOne is a function expression and so only defined when that line is reached, whereas functionTwo is a function declaration and is defined as soon as its surrounding function or script is executed (due to hoisting).

For example, a function expression:

// TypeError: functionOne is not a function
functionOne();

var functionOne = function() {
  console.log("Hello!");
};

Historically, function declarations defined within blocks were handled inconsistently between browsers. Strict mode (introduced in ES5) resolved this by scoping function declarations to their enclosing block.

'use strict';    
{ // note this block!
  function functionThree() {
    console.log("Hello!");
  }
}
functionThree(); // ReferenceError

Ref: https://bit.ly/2zMAj1O