Question

I’m trying to wrap up my script placeholderRX. All I need to do is get the ‘px’ off the end of the string returned from this call.

$(form).children('.inputSpan').each(function() {
   var $input = $(this)
   var $padding = $input.children('.input').css('padding-left');
});

This returns “6px”. I want to trim the 6 px off and make sure it’s an integer so I can then add 2 pixels to it and feed it to the css rule. I’m new to string manipulations in javascript. Help me out!

Answer 1

You can use a basic javascript replace(), parseInt(), or parseFloat() function to remove “px” from your result. Which method you use, depends on what exactly you need.

The following is a shortened version of your code using parse replace() to remove “px”.

$(form).children('.inputSpan').each(function() {
   var padding = $(this).children('.input').css('padding-left').replace("px", "");
});

In the above code, “16px” will return “16”. “16.7px” will return “16.7px”. “16em” will return “16em”.

---

The following is a shortened version of your code using parse parseInt() to remove “px” and more.

$(form).children('.inputSpan').each(function() {
   var padding = parseInt($(this).children('.input').css('padding-left'));
});

In the above code, “16px” will return “16”. “16.7px” will return “16”. “16em” will return “16”. As opposed to the first replace() example, this will remove any text, not just “px”.

---

The following is a shortened version of your code using parse parseDouble() to remove “px” and more.

$(form).children('.inputSpan').each(function() {
   var padding = parseDouble($(this).children('.input').css('padding-left'));
});

In the above code, “16px” will return “16”. “16.7px” will return “16.7”. “16em” will return “16”. As opposed to parseInt(), this keeps decimals, if you have them for some reason.

---

Of course, you can keep the code lengthy if there is a reason to see the broken up steps taken for future reference, or if the other variables are used for other reasons. This is the long version using parseInt().

$(form).children('.inputSpan').each(function() {
    var $input = $(this)
    var padding = $input.children('.input').css('padding-left');
    var paddingInt = parseInt(padding);
});

Also, to explain the change in the variable name from $padding to padding. A $ symbol in front of a javascript variable is common usage to distinguish regular javascript variables from jQuery variables, as they have different properties. There is no reason to use $padding because .css() does not return a jQuery object, but rather just a simple string.

In addition, for more complicated searches, you can research regular expressions.