See the Pen letters-numbers-field-1 by w3resource ( on CodePen. Javascript code function alphanumeric(inputtxt)Īlert('Your registration number have accepted : you can try another') Īlert('Please input alphanumeric characters only') JavaScript form validation - checking all letters and numbersĮnter your Registration Number and Submit Next the match() method of string object is used to match the said regular expression against the input value. a-z, A-Z or 0-9) we use a regular expression /^+$/ which allows only letters and numbers. To get a string contains only letters and numbers (i.e. Javascript function to check if a field input contains letters and numbers only // Function to check letters and numbers You can write a JavaScript form validation script to check whether the required field(s) in the HTML form contains only letters and numbers.

So you may want to rewrite your code as follows: function contains(a, obj) )) //falseĬonsole.log(.Sometimes situations arise ( suppose a user id, password or a code) when the user should fill a single or more than one field with alphabet characters (A-Z or a-z) and numbers (0-9) in an HTML form. reportArea() writes a square's area to a specific report list, given its length. Returns an object containing the square's size, position, and color.

draw() draws a square on a specified canvas, with a specified size, position, and color. If you need the best performance, benchmark for yourself in the relevant execution environments.Īs others have said, the iteration through the array is probably the best way, but it has been proven that a decreasing while loop is the fastest way to iterate in JavaScript. square.js contains: name a constant containing the string 'square'. If you need an easy solution, look for other answers.

It might not be relevant to modern JS execution contexts. The promised performance improvement was based on a benchmark done in browsers of that time. Update from 2019: This answer is from 2008 (11 years old!) and is not relevant for modern JS usage.

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