Resizing divs in Vanilla JavaScript.
Resize
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license: gpl-3.0 |
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<!DOCTYPE html> | |
<html> | |
<head> | |
<style> | |
body { | |
margin: 0; | |
width: 960px; | |
height: 500px; | |
outline: 1px solid gray; | |
} | |
#box-1 { | |
width: 300px; | |
height: 150px; | |
left: 300px; | |
top: 125px; | |
background: steelblue; | |
} | |
#box-2 { | |
width: 150px; | |
height: 300px; | |
left: 375px; | |
top: 100px; | |
background: tomato; | |
} | |
.box { | |
opacity: .8; | |
border: 2px solid black; | |
} | |
</style> | |
</head> | |
<body> | |
<div id="box-1" class="box"></div> | |
<div id="box-2" class="box"></div> | |
<script src="resize.js"></script> | |
<script> | |
resize("#box-1"); | |
resize("#box-2"); | |
</script> | |
</body> | |
</html> |
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function resize(selector){ | |
var element = document.querySelector(selector); | |
element.style.position = "absolute"; | |
var d = 8; // distance from cursor to border to active resizing | |
var rect = element.getBoundingClientRect(); | |
var rectLeft = rect.x || rect.left; | |
var rectWidth = rect.width; | |
var rectRight = rectLeft + rectWidth; | |
var rectTop = rect.y || rect.top; | |
var rectHeight = rect.height; | |
var rectBottom = rectTop + rectHeight; | |
var isLeft = false; | |
var isRight = false; | |
var isTop = false; | |
var isBottom = false; | |
var isResizable = _ => { isLeft || isRight || isTop || isBottom; }; | |
var isResizing = false; | |
var resizeStarted = false; | |
var isMouseDown = false; | |
function cursorStyle(){ | |
if (!isMouseDown){ | |
element.style.cursor = | |
isTop && isLeft ? "nwse-resize" : | |
isTop && isRight ? "nesw-resize" : | |
isBottom && isRight ? "nwse-resize" : | |
isBottom && isLeft ? "nesw-resize" : | |
isLeft ? "ew-resize" : | |
isRight ? "ew-resize" : | |
isTop ? "ns-resize" : | |
isBottom ? "ns-resize" : | |
"default"; | |
} | |
} | |
// just for testing | |
function cursorName(){ | |
return isTop && isLeft ? "TopLeft" : | |
isTop && isRight ? "TopRight" : | |
Bottom && Right ? "BottomRight" : | |
Bottom && Left ? "BottomLeft" : | |
Left ? "Left" : | |
Right ? "Right" : | |
Top ? "Top" : | |
Bottom ? "Bottom" : | |
"nothing"; | |
} | |
window.addEventListener("mousemove", _ => { | |
mouseX = event.clientX; | |
mouseY = event.clientY; | |
if (!isResizing){ | |
isLeft = Math.abs(mouseX - rectLeft) < d; | |
isRight = Math.abs(mouseX - rectRight) < d; | |
isTop = Math.abs(mouseY - rectTop) < d; | |
isBottom = Math.abs(mouseY - rectBottom) < d; | |
} | |
cursorStyle(); | |
isResizing = isMouseDown && isResizable; | |
if (isResizing){ | |
if (!resizeStarted){ | |
resizeStarted = true; | |
} | |
if (isRight){ | |
resizeRight(); | |
} | |
if (isLeft){ | |
resizeLeft(); | |
} | |
if (isTop){ | |
resizeTop(); | |
} | |
if (isBottom){ | |
resizeBottom(); | |
} | |
function resizeRight(){ | |
rectRight = mouseX; | |
rectWidth = rectRight - rectLeft; | |
element.style.width = rectWidth + "px"; | |
} | |
function resizeLeft(){ | |
rectLeft = mouseX >= rectRight ? rectRight : mouseX; | |
rectWidth = rectRight - rectLeft; | |
element.style.left = rectLeft + "px"; | |
element.style.width = rectWidth + "px"; | |
} | |
function resizeTop(){ | |
rectTop = mouseY >= rectBottom ? rectBottom : mouseY; | |
rectHeight = rectBottom - rectTop; | |
element.style.top = rectTop + "px"; | |
element.style.height = rectHeight + "px"; | |
} | |
function resizeBottom(){ | |
rectBottom = mouseY; | |
rectHeight = rectBottom - rectTop; | |
element.style.height = rectHeight + "px"; | |
} | |
} | |
}); | |
element.onmousedown = _ => { | |
isMouseDown = true; | |
} | |
element.onmouseup = _ => { | |
isMouseDown = false; | |
} | |
} |
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