How do you get a translateX
, translateY
or translateZ
value in JavaScript?
Turns out, you need to read transform matrices. But it can be quite easy.
Matrices
Browsers turn transform
values into 2d
or 3d
matrices depending on what transformations you applied.
 Browsers create
3d
matrices if you apply 3d transforms (X, Y, Z axes).  Browsers create
2d
matrices if you apply 2d transforms (X, Y axes only).
We can get the matrix via JavaScript with getComputedStyle
.
const style = window.getComputedStyle(element);
const matrix = style.transform  style.webkitTransform  style.mozTransform;
Let's have a look at some examples:
.twod {
transform: translateX(10px) translateY(20px);
}
.threed {
transform: translateX(10px) translateY(20px) translateZ(30px);
}
2d vs 3d matrices
Pay attention to the matrix values above. You may notice this:
2d Matrix
A 2d matrix has 6
values.
 5th value is
translateX
 6th value is
translateY
3d Matrix
A 3d matrix has 16
values.
 13th value is
translateX
 14th value is
translateY
 15th value is
translateZ
Getting the translate values
Once we know the pattern, extracting the values is easy. First, we need to know which matrix we're dealing with.
const style = window.getComputedStyle(element);
const matrix = style.transform  style.webkitTransform  style.mozTransform;
// Can either be 2d or 3d transform
const matrixType = matrix.includes("3d") ? "3d" : "2d";
If the Matrix is 2d
, we can get values translateX
and translateY
values like this:
const matrixValues = matrix.match(/matrix.*\((.+)\)/)[1].split(", ");
if (matrixType === "2d") {
const x = matrixValues[4];
const y = matrixValues[5];
}
If the Matrix is 3d
, we can get values translateX
, translateY
, and translateZ
values like this:
const matrixValues = matrix.match(/matrix.*\((.+)\)/)[1].split(", ");
if (matrixType === "3d") {
const x = matrixValues[12];
const y = matrixValues[13];
const z = matrixValues[14];
}
I packed this up into a nice function for us to use.
/**
* Gets computed translate values
* @param {HTMLElement} element
* @returns {Object}
*/
function getTranslateValues(element) {
const style = window.getComputedStyle(element);
const matrix = style.transform  style.webkitTransform  style.mozTransform;
// No transform property. Simply return 0 values.
if (matrix === "none") {
return {
x: 0,
y: 0,
z: 0,
};
}
// Can either be 2d or 3d transform
const matrixType = matrix.includes("3d") ? "3d" : "2d";
const matrixValues = matrix.match(/matrix.*\((.+)\)/)[1].split(", ");
// 2d matrices have 6 values
// Last 2 values are X and Y.
// 2d matrices does not have Z value.
if (matrixType === "2d") {
return {
x: matrixValues[4],
y: matrixValues[5],
z: 0,
};
}
// 3d matrices have 16 values
// The 13th, 14th, and 15th values are X, Y, and Z
if (matrixType === "3d") {
return {
x: matrixValues[12],
y: matrixValues[13],
z: matrixValues[14],
};
}
}
Using it:
const { x, y, z } = getTranslateValues(element);
ðŸ’¥.
Simple transforms only
getTranslateValues
works only if translate
is declared before other transforms. This is because transform values stack onto each other.
Let's explain this with a 2d matrix example.
Let's say you have this element.
.element {
transform: translateX(10px) translateY(20px);
}
You already know these:
 5th number is
10
which is the same value astranslateX
 6th number is
20
, which is the same value astranslateY
Now let's add a rotate
transformation behind translateX
and translateY
.
.element {
transform: translateX(10px) translateY(20px) rotate(10deg);
}
There's no difference in the 5th and 6th values:
 5th number is
10
which is the same value astranslateX
 6th number is
20
, which is the same value astranslateY
But watch what happens if you rotate
first.
.element {
transform: rotate(10deg) translateX(10px) translateY(20px);
}
 5th number is
6.37511
which is the NOT what we wrote fortranslateX
 6th number is
21.4326
, which is the NOT what we wrote fortranslateY
Just take note of this!
Getting other transform values in JavaScript
I haven't had the chance to deal with scale
, skew
, and rotate
yet, but I was curious. So I googled and found some answers:

rotate
on on CSS Tricks 
scale
on Michael Le's blog  both
rotate
+skew
on this Stack overflow answer
I believe the calculations work with individual transforms. I'm not so sure they work if transformations are stacked on top of each other. (For example, skew > rotate
gives a very different value compared to rotate > skew
).
Keep it simple, I guess!
Useful JavaScript Snippets repository
I added this code to a Github repository that contains JavaScript snippets I found useful. You may be interested in checking it out.
Thanks for reading. This article was originally posted on my blog. Sign up for my newsletter if you want more articles to help you become a better frontend developer.
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