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| var DEFAULT_DURATION, DEFAULT_TOP_OFFSET, EASE_IN_OUT, GetPositionMixin, MAXIMUM_SCROLL_ATTEMPTS, POSITION, React, ScrollTo, _;
React = require('react');
_ = require('underscore');
GetPositionMixin = require('openstax-react-components').GetPositionMixin;
DEFAULT_DURATION = 750;
DEFAULT_TOP_OFFSET = 80;
MAXIMUM_SCROLL_ATTEMPTS = 3;
EASE_IN_OUT = function(t) {
Eif (t < .5) {
return 4 * t * t * t;
} else {
return (t - 1) * (2 * t - 2) * (2 * t - 2) + 1;
}
};
POSITION = function(start, end, elapsed, duration) {
Iif (elapsed > duration) {
return end;
}
return start + (end - start) * EASE_IN_OUT(elapsed / duration);
};
ScrollTo = {
getDefaultProps: function() {
return {
windowImpl: window
};
},
componentDidMount: function() {
var hash;
React.findDOMNode(this).addEventListener('click', this._onScrollClick, false);
hash = this.props.windowImpl.location.hash;
if (hash) {
this.props.windowImpl.location.hash = "";
(typeof this.waitToScrollToSelector === "function" ? this.waitToScrollToSelector(hash) : void 0) || this.scrollToSelector(hash);
}
return this.props.windowImpl.addEventListener('hashchange', this._onHashChange, false);
},
componentWillUnmount: function() {
React.findDOMNode(this).removeEventListener('click', this._onScrollClick, false);
return this.props.windowImpl.removeEventListener('hashchange', this._onHashChange, false);
},
scrollToSelector: function(selector) {
var el, root;
Iif (_.isEmpty(selector)) {
return;
}
root = React.findDOMNode(this);
el = root.querySelector(selector);
Eif (el) {
return this.scrollToElement(el);
}
},
_onHashChange: function() {
Eif (this.props.windowImpl.location.hash) {
return this.scrollToSelector(this.props.windowImpl.location.hash);
}
},
_onScrollClick: function(ev) {
if (ev.target.tagName !== 'A') {
return;
}
if (this.scrollToSelector(ev.target.hash)) {
return ev.preventDefault();
}
},
_desiredTopPosition: function(el) {
return GetPositionMixin.getTopPosition(el) - _.result(this, 'getScrollTopOffset', DEFAULT_TOP_OFFSET);
},
_onBeforeScroll: function(el) {
el.classList.add('target-scroll');
return typeof this.onBeforeScroll === "function" ? this.onBeforeScroll(el) : void 0;
},
_onAfterScroll: function(el) {
var ref;
if (el != null ? (ref = el.classList) != null ? ref.contains('target-scroll') : void 0 : void 0) {
_.delay(el.classList.remove.bind(el.classList, 'target-scroll'), 150);
}
this.props.windowImpl.history.pushState(null, null, "#" + el.id);
return typeof this.onAfterScroll === "function" ? this.onAfterScroll(el) : void 0;
},
_onScrollStep: function(el, attemptNumber) {
if (attemptNumber < MAXIMUM_SCROLL_ATTEMPTS && this.props.windowImpl.pageYOffset !== this._desiredTopPosition(el)) {
return this.scrollToElement(el, attemptNumber + 1);
} else {
return this._onAfterScroll(el);
}
},
scrollToElement: function(el, attemptNumber) {
var duration, endPos, requestAnimationFrame, startPos, startTime, step, win;
Eif (attemptNumber == null) {
attemptNumber = 0;
}
win = this.props.windowImpl;
startPos = win.pageYOffset;
endPos = this._desiredTopPosition(el);
startTime = Date.now();
duration = _.result(this, 'getScrollDuration', DEFAULT_DURATION);
requestAnimationFrame = win.requestAnimationFrame || _.defer;
step = (function(_this) {
return function() {
var elapsed;
elapsed = Date.now() - startTime;
win.scroll(0, POSITION(startPos, endPos, elapsed, duration));
Eif (elapsed < duration) {
return requestAnimationFrame(step);
} else {
return _this._onScrollStep(el, attemptNumber);
}
};
})(this);
this._onBeforeScroll(el);
return step();
}
};
module.exports = ScrollTo;
|