javascript 事件屏蔽问题

大家好，我现在 .....
现在两个click事件都会调用如何在点击 checkbox 时屏蔽掉外部click事件

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

阻止JavaScript事件冒泡传递（cancelBubble 、stopPropagation）
function doSomething (obj,evt) { alert(obj.id); var e=(evt)?evt:window.event; if (window.event) { e.cancelBubble=true; } else { //e.preventDefault(); e.stopPropagation(); } }

This is parent1 div.

This is child1.

This is parent1 div.

This is parent2 div.

This is child2. Will bubble.

This is parent2 div.

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