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utils/loadScript.ts

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+const callbacks: any = {};
+
+/**
+ * 加载一个远程脚本
+ * @param {String} src 一个远程脚本
+ * @param {Function} callback 回调
+ */
+function loadScript(src: string, callback: { (): void; (): void }) {
+  const existingScript = document.getElementById(src);
+  const cb = callback || (() => {});
+  if (!existingScript) {
+    callbacks[src] = [];
+    const $script: HTMLScriptElement = document.createElement('script');
+    $script.src = src;
+    $script.id = src;
+    $script.async = Boolean(1);
+    document.body.appendChild($script);
+    const onEnd = 'onload' in $script ? stdOnEnd.bind($script) : ieOnEnd.bind($script);
+    // @ts-ignore
+    onEnd($script);
+  }
+
+  callbacks[src].push(cb);
+
+  function stdOnEnd(script: { onload?: () => void; onerror: () => void }) {
+    script.onload = () => {
+      // @ts-ignore
+      this.onerror = this.onload = null;
+      callbacks[src].forEach(
+        (item: (arg0: null, arg1: { onload?: (() => void) | undefined; onerror: () => void }) => void) => {
+          item(null, script);
+        }
+      );
+      delete callbacks[src];
+    };
+    script.onerror = () => {
+      // @ts-ignore
+      this.onerror = this.onload = null;
+      // @ts-ignore
+      cb(new Error(`Failed to load ${src}`), script);
+    };
+  }
+
+  function ieOnEnd(script: { onreadystatechange: () => void }) {
+    script.onreadystatechange = () => {
+      // @ts-ignore
+      if (this.readyState !== 'complete' && this.readyState !== 'loaded') return;
+      // @ts-ignore
+      this.onreadystatechange = null;
+      callbacks[src].forEach((item: (arg0: null, arg1: { onreadystatechange: () => void }) => void) => {
+        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: any[], cb: { (): void; (): void }) {
+  const first = list.shift();
+  list.length ? loadScript(first, () => loadScriptQueue(list, cb)) : loadScript(first, cb);
+}
+
+export default loadScript;