//封装loadscript要领
export function loadScript(url, callback) {
var script = document.createElement("script");
script.type = "text/javascript"
if (script.readyState) {
script.onreadystatechange = function () {
if (script.readyState == "loaded" || script.readyState == "complete") {
script.onreadystatechange = null
callback()
}
}
} else {
script.onload = function () {
callback()
}
}
script.src = url
document.getElementsByName("head")[0].appendChild(script)
}
//嵌套运用
loadScript("file1.js", function () {
loadScript("file2.js", function () {
loadScript("file3.js", function () {
alert("All files are loaded!")
})
})
})