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Support: improve support properties computation

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* Remove div from the memory if it is not needed anymore

* Make `computeStyleTests` method a singleton

Fixes gh-3018
Closes gh-3021
This commit is contained in:
Oleg Gaidarenko
2016-03-28 16:11:39 +03:00
parent e8ff8176fc
commit 44cb97e0cf
1 changed files with 15 additions and 19 deletions
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34
src/css/support.js
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@@ -28,6 +28,12 @@ define( [
// Executing both pixelPosition & boxSizingReliable tests require only one layout
// so they're executed at the same time to save the second computation.
function computeStyleTests() {
// This is a singleton, we need to execute it only once
if ( !div ) {
return;
}
div.style.cssText =
"box-sizing:border-box;" +
"position:relative;display:block;" +
@@ -38,6 +44,8 @@ define( [
var divStyle = window.getComputedStyle( div );
pixelPositionVal = divStyle.top !== "1%";
// Support: Android 4.0 - 4.3 only, Firefox <=3 - 44+
reliableMarginLeftVal = divStyle.marginLeft === "2px";
boxSizingReliableVal = divStyle.width === "4px";
@@ -47,39 +55,27 @@ define( [
pixelMarginRightVal = divStyle.marginRight === "4px";
documentElement.removeChild( container );
// Nullify the div so it wouldn't be stored in the memory and
// it will also be a sign that checks already performed
div = null;
}
jQuery.extend( support, {
pixelPosition: function() {
// This test is executed only once but we still do memoizing
// since we can use the boxSizingReliable pre-computing.
// No need to check if the test was already performed, though.
computeStyleTests();
return pixelPositionVal;
},
boxSizingReliable: function() {
if ( boxSizingReliableVal == null ) {
computeStyleTests();
}
computeStyleTests();
return boxSizingReliableVal;
},
pixelMarginRight: function() {
// Support: Android 4.0 - 4.3 only
// We're checking for boxSizingReliableVal here instead of pixelMarginRightVal
// since that compresses better and they're computed together anyway.
if ( boxSizingReliableVal == null ) {
computeStyleTests();
}
computeStyleTests();
return pixelMarginRightVal;
},
reliableMarginLeft: function() {
// Support: Android 4.0 - 4.3 only, Firefox <=3 - 44+
if ( boxSizingReliableVal == null ) {
computeStyleTests();
}
computeStyleTests();
return reliableMarginLeftVal;
}
} );