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JavaScript: Truncate a string if it is longer than the specified number of characters

JavaScript String: Exercise-16 with Solution

Write a JavaScript function to truncate a string if it is longer than the specified number of characters. Truncated strings will end with a translatable ellipsis sequence ("…") (by default) or specified characters.

Test Data:
console.log(text_truncate('We are doing JS string exercises.'))
console.log(text_truncate('We are doing JS string exercises.',19))
console.log(text_truncate('We are doing JS string exercises.',15,'!!'))
"We are doing JS string exercises."
"We are doing JS ..."
"We are doing !!"

Sample Solution:-

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JS truncates a string</title>
</head>
<body>
</body>
</html>

JavaScript Code:

text_truncate = function(str, length, ending) {
    if (length == null) {
      length = 100;
    }
    if (ending == null) {
      ending = '...';
    }
    if (str.length > length) {
      return str.substring(0, length - ending.length) + ending;
    } else {
      return str;
    }
  };
console.log(text_truncate('We are doing JS string exercises.'))
console.log(text_truncate('We are doing JS string exercises.',19))
console.log(text_truncate('We are doing JS string exercises.',15,'!!'))

Sample Output:

We are doing JS string exercises.
We are doing JS ...
We are doing !!

Flowchart:

Flowchart: JavaScript- Truncate a string if it is longer than the specified number of characters

Live Demo:

See the Pen JavaScript Truncate a string if it is longer than the specified number of characters - string-ex-16 by w3resource (@w3resource) on CodePen.


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Previous: Write a JavaScript function to humanized number (Formats a number to a human-readable string.) with the correct suffix such as 1st, 2nd, 3rd or 4th.
Next: Write a JavaScript function to chop a string into chunks of a given length.

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JavaScript: Tips of the Day

How to check whether a string contains a substring in JavaScript?

ECMAScript 6 introduced String.prototype.includes:

const string = "foo";
const substring = "oo";

console.log(string.includes(substring));

includes doesn't have Internet Explorer support, though. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found: 

var string = "foo";
var substring = "oo";

console.log(string.indexOf(substring) !== -1);

Ref: https://bit.ly/3fFFgZv