JavaScript chop/slice/trim off last character in s

Question

I have a string, 12345.00, and I would like it to return 12345.0.

I have looked at trim, but it looks like it is only trimming whitespace and slice which I don't see how this would work. Any suggestions?

Answer 1

You can use the substring function:

let str = "12345.00";
str = str.substring(0, str.length - 1);
console.log(str);

This is the accepted answer, but as per the conversations below, the slice syntax is much clearer:

let str = "12345.00";
str = str.slice(0, -1); 
console.log(str);

Answer 2

Here is an alternative that i don't think i've seen in the other answers, just for fun.

var strArr = "hello i'm a string".split("");
strArr.pop();
document.write(strArr.join(""));

Not as legible or simple as slice or substring but does allow you to play with the string using some nice array methods, so worth knowing.

Answer 3

debris = string.split("_") //explode string into array of strings indexed by "_"

debris.pop(); //pop last element off the array (which you didn't want)

result = debris.join("_"); //fuse the remainng items together like the sun

Answer 4

If you want to do generic rounding of floats, instead of just trimming the last character:

var float1 = 12345.00,
    float2 = 12345.4567,
    float3 = 12345.982;

var MoreMath = {
    /**
     * Rounds a value to the specified number of decimals
     * @param float value The value to be rounded
     * @param int nrDecimals The number of decimals to round value to
     * @return float value rounded to nrDecimals decimals
     */
    round: function (value, nrDecimals) {
        var x = nrDecimals > 0 ? 10 * parseInt(nrDecimals, 10) : 1;
        return Math.round(value * x) / x;
    }
}

MoreMath.round(float1, 1) => 12345.0
MoreMath.round(float2, 1) => 12345.5
MoreMath.round(float3, 1) => 12346.0

EDIT: Seems like there exists a built in function for this, as Paolo points out. That solution is obviously much cleaner than mine. Use parseFloat followed by toFixed

Answer 5

The easiest method is to use the slice method of the string, which allows negative positions (corresponding to offsets from the end of the string):

const s = "your string";
const withoutLastFourChars = s.slice(0, -4);

If you needed something more general to remove everything after (and including) the last underscore, you could do the following (so long as s is guaranteed to contain at least one underscore):

const s = "your_string";
const withoutLastChunk = s.slice(0, s.lastIndexOf("_"));
console.log(withoutLastChunk);

Answer 6

Use regex:

let aStr = "12345.00";
aStr = aStr.replace(/.$/, '');
console.log(aStr);