const callbacks = {}
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/**
|
* 加载一个远程脚本
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* @param {String} src 一个远程脚本
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* @param {Function} callback 回调
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*/
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function loadScript(src, callback) {
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const existingScript = document.getElementById(src)
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const cb = callback || (() => {})
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if (!existingScript) {
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callbacks[src] = []
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const $script = document.createElement('script')
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$script.src = src
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$script.id = src
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$script.async = 1
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document.body.appendChild($script)
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const onEnd = 'onload' in $script ? stdOnEnd.bind($script) : ieOnEnd.bind($script)
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onEnd($script)
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}
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|
callbacks[src].push(cb)
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|
function stdOnEnd(script) {
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script.onload = () => {
|
this.onerror = this.onload = null
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callbacks[src].forEach(item => {
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item(null, script)
|
})
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delete callbacks[src]
|
}
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script.onerror = () => {
|
this.onerror = this.onload = null
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cb(new Error(`Failed to load ${src}`), script)
|
}
|
}
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|
function ieOnEnd(script) {
|
script.onreadystatechange = () => {
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if (this.readyState !== 'complete' && this.readyState !== 'loaded') return
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this.onreadystatechange = null
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callbacks[src].forEach(item => {
|
item(null, script)
|
})
|
delete callbacks[src]
|
}
|
}
|
}
|
|
/**
|
* 顺序加载一组远程脚本
|
* @param {Array} list 一组远程脚本
|
* @param {Function} cb 回调
|
*/
|
export function loadScriptQueue(list, cb) {
|
const first = list.shift()
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list.length ? loadScript(first, () => loadScriptQueue(list, cb)) : loadScript(first, cb)
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}
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|
export default loadScript
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