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DOM events allow event-driven programming languages like JavaScript, JScript, ECMAScript, VBScript and Java to register various event handlers/listeners on the element nodes inside a DOM tree, e.g. HTML, XHTML, XUL and SVG documents. Historically, like DOM, the event models used by various web browsers had some significant differences. This caused compatibility problems. To combat this, the event model was standardized by the W3C in DOM Level 2.