gulp-defer
v1.1.2
Published
Moves render blocking javascript and css into a deferred loading section
Downloads
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Readme
gulp-defer
Moves render blocking javascript and css into a deferred loading section.
It is likely to be helpful if you get "Eliminate render-blocking JavaScript and CSS in above-the-fold content" warning from PageSpeed Insights results
See https://varvy.com/pagespeed/defer-loading-javascript.html for more information on how to address this warning
Installation
npm install gulp-deferUsage
Example gulp task:
var gulp = require("gulp"),
defer = require("gulp-defer");
gulp.task('html:release', function() {
return gulp.src(conf.tmp_dir + '/*.html')
.pipe($.usemin({
css: [
$.minifyCss(),
'concat',
$.rev()
],
js: [
$.uglify(),
$.rev()
]
}))
.pipe(defer())
.pipe(gulp.dest(conf.dist_dir));
});
Blocks
Blocks are expressed as:
<!--defer-->
<script src="js/app.js"></script>
<script src="js/controllers/thing-controller.js"></script>
<script src="js/models/thing-model.js"></script>
<script src="js/views/thing-view.js"></script>
<!--enddefer-->An example of a page using defer blocks ca be seen below:
<!DOCTYPE HTML>
<html>
<head>
<title></title>
<meta charset="utf-8">
<!--defer-->
<link rel="stylesheet" href="css/font.css"/>
<!--enddefer-->
<!--defer-->
<script type="text/javascript" src="js/libs/vendor/jquery.min.js"></script>
<script type="text/javascript" src="js/libs/vendor/isMobile.min.js"></script>
<!--enddefer-->
</head>
<body>
<div id="content" class="content">
Loading...
</div>
</body>
</html>The result after processing with gulp-defer will be:
<!DOCTYPE HTML>
<html>
<head>
<title></title>
<meta charset="utf-8">
</head>
<body>
<div id="content" class="content">
Loading...
</div>
<script type="text/javascript">!function (a, b, c) { "use strict"; var d = function (a) { if ("[object Array]" !== Object.prototype.toString.call(a))return !1; for (var c = 0; c < a.length; c++) { var d = b.createElement("script"), e = a[c]; d.src = e.src, d.async = e.async, b.body.appendChild(d) } return !0 }; var e = function (a) { if ("[object Array]" !== Object.prototype.toString.call(a))return !1; for (var c = 0; c < a.length; c++) { var d = document.createElement("link"), e = a[c]; d.rel = "stylesheet", d.href = e.href, document.getElementsByTagName("head")[0].appendChild(d); } return !0 }; a.addEventListener ? a.addEventListener("load", function () { d(c.scripts); e(c.styles); }, !1) : a.attachEvent ? a.attachEvent("onload", function () { d(c.scripts); e(c.styles); }) : a.onload = function () { d(c.scripts); e(c.styles); } }(window, document, {"scripts":[{"src":"js/libs/vendor/jquery.min.js","async":false},{"src":"js/libs/vendor/isMobile.min.js","async":false}],"styles":[{"href":"css/font.css"}]});</script>
</body>
</html>injected script
Contents of injected scrpipt in an above example listed below
! function(a, b, c) {
"use strict";
var d = function(a) {
if ("[object Array]" !== Object.prototype.toString.call(a)) return !1;
for (var c = 0; c < a.length; c++) {
var d = b.createElement("script"),
e = a[c];
d.src = e.src, d.async = e.async, b.body.appendChild(d)
}
return !0
};
var e = function(a) {
if ("[object Array]" !== Object.prototype.toString.call(a)) return !1;
for (var c = 0; c < a.length; c++) {
var d = document.createElement("link"),
e = a[c];
d.rel = "stylesheet", d.href = e.href, document.getElementsByTagName("head")[0].appendChild(d);
}
return !0
};
a.addEventListener ? a.addEventListener("load", function() {
d(c.scripts);
e(c.styles);
}, !1) : a.attachEvent ? a.attachEvent("onload", function() {
d(c.scripts);
e(c.styles);
}) : a.onload = function() {
d(c.scripts);
e(c.styles);
}
}(window, document, {
"scripts": [{
"src": "js/libs/vendor/jquery.min.js",
"async": false
}, {
"src": "js/libs/vendor/isMobile.min.js",
"async": false
}],
"styles": [{
"href": "css/font.css"
}]
});