Check if the last char is dot (.)

Question

I need to check if the last character of an input (type="number") value is a dot!

Tried these, but it doesn't work:

let amount = $("#amount").val();
let last_char = amount.slice(-1);
if(last_char == ".")
{
    return;
}

Also tried amount[amount.length-1] and charAt()

P.S. Input type is type="number"

Edit:

What's the use case here? You could use regex to detect the period, look here for a succinct answer: https://stackoverflow.com/questions/32657021/check-if-string-begins-with-punctuation-javascript — Nathaniel Flick, Sep 27 '19 at 04:41
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/endsWith — Durga, Sep 27 '19 at 04:47
Possible duplicate of [endsWith in JavaScript](https://stackoverflow.com/questions/280634/endswith-in-javascript) — User863, Sep 27 '19 at 05:03
@User863 It is not a duplicate: https://jsfiddle.net/dne37hao/ — J. Doe, Sep 27 '19 at 05:11
@J.Doe Technically `3.` is equal to `3` https://stackoverflow.com/questions/18852244/how-to-get-the-raw-value-an-input-type-number-field — User863, Sep 27 '19 at 05:32
The problem here isn't the matching for the last character. The problem is that, whilst reading the field value with a dot in the end its being interpreted as an empty field. So that's why your checks for the last character are not matching. This question will help you https://stackoverflow.com/questions/18677323/html5-input-type-number-value-is-empty-in-webkit-if-has-spaces-or-non-numeric-ch — noa-dev, Sep 27 '19 at 05:57

score 3 · Answer 1 · answered Sep 27 '19 at 04:58

3

const string = 'Is this a question.';

console.log(string.endsWith('.'));

answered Sep 27 '19 at 04:58

Rohit Kumar

score 1 · Answer 2 · answered Sep 27 '19 at 05:00

1

You can achieve this using different ways but with different performance,

1. Using bracket notation:

var str = "Test";
var lastLetter = str[str.length - 1];

But it's not recommended to use brackets.

2. charAt[index]:

var lastLetter = str.charAt(str.length - 1)

This is readable and fastest among others. It is most recommended way.

3. substring:

str.substring(str.length - 1);

4. slice:

if(str.slice(-1)=== '.'){
return true
}

It's slightly faster than substring.The most efficient one

With ES6:

You can use str.endsWith("t");

answered Sep 27 '19 at 05:00

1

This doesn't answer OP's question – adiga Sep 27 '19 at 05:42
@adiga can you please elaborate? how it does't answer his question. i have listed down 4 different methods with examples and performance. – Abdul Basit Mangat Oct 01 '19 at 09:44
The issue is caused by `type="number"` in the input. `.val()` will ignore the trailing dot. Check the fiddle. – adiga Oct 01 '19 at 09:52

score -2 · Answer 3 · edited Sep 27 '19 at 09:54

-2

You can try this:

let amount = $("#amount").val();
if(amount[amount.length-1] === "."){
   return true;
}

edited Sep 27 '19 at 09:54

Dino

answered Sep 27 '19 at 04:52

virender nehra

what value are you getting in amount variable any example ? – virender nehra Sep 27 '19 at 04:58
For example: `1.` `36.` it doesn't skip these. input type is also number – J. Doe Sep 27 '19 at 05:01
So jquery .val() method return string, javascript convert number to string and ignore the . in the end. so if you print amount in console it never show dot(.) in the end, change input type as text then you can check if input has a dot in the end or not. – virender nehra Sep 27 '19 at 05:06
Number can not end with dot in javascript, javascript basically ignore . in the end of the number – virender nehra Sep 27 '19 at 05:19