CODEWITHSUNDEEP
javascriptconditional-statements
Ali
Ali

Reputation: 10463

How to check condition in JavaScript with ASCII value?

I'm trying to do a validation for the input field and wanted to check if it's a special character or not

so I though I can check that with ASCII value but not sure how is that done in JavaScript language.

In C I can just check with the string of array right away.

if (input < 4 && document.myTable.inputField.value[0] < 65 )

I want to check if it's they have less than four character and those are special characters if yes I will give them an error message else just do nothing.

Upvotes: 0

Views: 3980

Answers (3)

KooiInc
KooiInc

Reputation: 122956

You can use the charCodeAt method of String to determine the ASCII code at a certain position. Assuming that by input you mean the input field, this would be a way to do it:

var input = document.myTable.inputField.value;
if (input.length < 4 && input.charCodeAt(0) < 65 ) { /* etc. */ }
// examples charCodeAt
'foo'.charCodeAt(0);  //=> 102
'-foo'.charCodeAt(0); //=> 45

Upvotes: 1

Diego
Diego

Reputation: 18359

You can use regular expressions. I think that's easier to read. For example: (/a-z/gi).test(myString) returns true if myString contains anything except letters (upper or lower case). So your condition can be changed to:

if (input < 4 && !(/a-z/gi).test(document.myTable.inputField.value))

Upvotes: 2

Ignacio Vazquez-Abrams
Ignacio Vazquez-Abrams

Reputation: 799150

In C, brute force checking is the cleanest and easiest alternative. In JavaScript, it is not.

js> /^[A-Za-z]+$/.test('foo')
true
js> /^[A-Za-z]+$/.test('bar123')
false

Upvotes: 3

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