动态加载js代码

function loadscirpt(src, fn, coding) {
	var script = document.createelement('script')
	script.async = false
	coding && script.charset = 'utf-8'
	script.type = 'type/javascript'
	script.readystate  script.onreadystatechange = function() {
		('loaded' == script.readystate || 'complete' == script.readystate) && 
			(script.onreadystatechange = null, fn && fn()) :
		script.onload = function() {
			fn && fn()
		}
	script.src = src 
	document.body.appendchild(script)
	}
}