Python's strip function is used to remove given characters from the beginning and end of the string. How to create a similar function in javascript?

Example:

str = "'^$   *# smart kitty &  ''^$*   '^";
newStr = str.strip(" '^$*#&");
console.log(newStr);

Output:

smart kitty

• javascript
• python

A simple but not very effective way would be to look for the characters and remove them:

function strip(str, remove) {
  while (str.length > 0 && remove.indexOf(str.charAt(0)) != -1) {
    str = str.substr(1);
  }
  while (str.length > 0 && remove.indexOf(str.charAt(str.length - 1)) != -1) {
    str = str.substr(0, str.length - 1);
  }
  return str;
}

A more effective, but not as easy to use, would be a regular expression:

str = str.replace(/(^[ '\^\$\*#&]+)|([ '\^\$\*#&]+$)/g, '')

Note: I escaped all characters that have any special meaning in a regular expression. You need to do that for some characters, but perhaps not all the ones that I escaped here as they are used inside a set. That's mostly to point out that some characters do need escaping.

There's lodash's trim()

Removes leading and trailing whitespace or specified characters from string.

_.trim('  abc  ');             // → 'abc'

_.trim('-_-abc-_-', '_-');     // → 'abc'

Modifying a code snippet from Mozilla Developer Network String.prototype.trim(), you could define such a function as follows.

if (!String.prototype.strip) {
  String.prototype.strip = function (string) {
    var escaped = string.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1");
    return this.replace(RegExp("^[" + escaped + "]+|[" + escaped + "]+$", "gm"), '');
  };
}

It's not necessary and probably not advisable to put this function in the object String.prototype, but it does give you a clear indication of how such a function compares with the existing String.prototype.trim().

The value of escaped is as in the function escapeRegExp in the guide to Regular Expressions. The Java programming language has a standard library function for that purpose, but JavaScript does not.

Not exactly... I would use regex for complicated string manipulation or the Slice() method to remove characters at certain points Slice() explained