基础知识记录修改

js/promise研究/顺序执行.js

@@ -0,0 +1,73 @@
+
+function handle(promise){
+    return promise.then(data=>[null,data]).catch(err=>[err,null])
+}
+
+function fn1(){
+    return new Promise((resolve,reject)=>{
+        setTimeout(()=>{
+            console.log('fn1');
+            resolve('ffn1');
+        },1000)
+    })
+}
+
+function fn2(){
+    return new Promise((resolve,reject)=>{
+        setTimeout(()=>{
+            console.log('fn2');
+            resolve('ffn2');
+        },1000)
+    })
+}
+
+function rejectFn(){
+    return new Promise((resolve,reject)=>{
+        setTimeout(()=>{
+            console.log('rejectFn');
+            reject('rejectFn');
+        },1000)
+    })
+}
+
+async function test1(){
+    let time1 = new Date().getTime();
+    let f1 = fn1();
+    let f2 = fn2();
+    let res1 = await f1;
+    let res2 = await f2;
+    console.log(res1,res2);
+    let time2 = new Date().getTime();
+    console.log(time2-time1);
+}
+
+// test1(); // 1012ms
+
+
+async function test2(){
+    let time1 = new Date().getTime();
+    let res1 = await fn1();
+    let res2 = await fn2();
+    console.log(res1,res2);
+    let time2 = new Date().getTime();
+    console.log(time2-time1);
+}
+
+// test2(); // 2021ms
+
+async function test3(){
+    let time1 = new Date().getTime();
+    let f1 = fn1();
+    let f2 = fn2();
+    let r3 = rejectFn();
+    let [err,res] = await handle(f1);
+    let [err2,res2] = await handle(f2);
+    let [err3,res3] = await handle(r3);
+    console.log(err,res);
+    console.log(err2,res2);
+    console.log(err3,res3);
+    let time2 = new Date().getTime();
+    console.log(time2-time1);
+}
+
+test3(); // 1023ms