MY 总结:js return true,return false

本文通过一个具体的JavaScript示例展示了return true与return false在实际应用中的区别。通过按钮触发的不同返回值,演示了如何控制页面行为,如阻止默认操作或允许表单提交等。

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  1. <script>
  2. functionwindow.onload(){
  3. alert("onload!");
  4. alert("check(1):::returntrue测试::"+check(1));//弹出提示:check(1):::returntrue测试::true
  5. alert("check(0):::returnfalse测试::"+check(0));//弹出提示:check(2):::returnfalse测试::false
  6. }
  7. /*
  8. returnfalse表示返回一个false值,也就是说提交是不成功的。错误之后的js代码不会再运行
  9. returntrue表法返回一个true值,也就是提交了。
  10. */
  11. functioncheck(p)
  12. {
  13. if(p==0)
  14. {
  15. alert("returnfalse测试");
  16. returnfalse;
  17. alert("执行returnfalse以后");//return语句后的语句都不再执行测试带有action时,是否执行action
  18. }
  19. else
  20. {
  21. //return"ispanda";//如果是执行本句,则返回:“ispanda”
  22. alert("returntrue测试");
  23. returntrue;
  24. alert("执行returntrue以后");//return语句后的语句都不再执行
  25. }
  26. alert("if、else中的returnture/false语句没有起作用!");//return语句后的语句都不再执行
  27. }
  28. </script>
  29. <html>
  30. <head>
  31. <TITLE>解决jsreturntrue/false的问题</TITLE>
  32. <inputtype="button"value="测试"onClick="check(0)"/>
  33. </head>
  34. <body>
  35. </body>
  36. </html>
@app.callback( [Output("my-modal", "is_open"), Output("success-modal", "is_open")], [Input("submit-btn", "n_clicks"), Input("custom-close-icon", "n_clicks"), Input("close-modal", "n_clicks")], [State("my-modal", "is_open"), State("sn", "value"), State("ip", "value"), State("fp", "value"), State("type", "value"), State("pi-ip", "value")], prevent_initial_call=True ) def handle_modal_actions(submit_clicks, custom_close_clicks, close_clicks, is_open, sn, ip, fp, device_type, pi_ip): ctx = dash.callback_context if not ctx.triggered: return dash.no_update trigger_id = ctx.triggered[0]["prop_id"].split(".")[0] print(f"trigger_id={trigger_id}") if trigger_id == "custom-close-icon": return not is_open, dash.no_update if trigger_id == "submit-btn": if not all([sn, ip, fp, device_type]): logging.warning("Missing required fields") return dash.no_update try: # 动态构建SQL语句 columns = ["serialnumber", "dut_ip", "floorplan", "device_type", "pi_ip", "team", "available"] values = [sn, ip, fp, device_type, "", "local", "1"] if pi_ip: columns.append("pi_ip") values.append(pi_ip) query = f""" INSERT INTO devices ({', '.join(columns)}) VALUES ({', '.join(['%s'] * len(values))}) """ # 执行数据库操作 success = db_execute(query, tuple(values)) if success: print("Database operation successful, closing my-modal and opening success-modal") return False, True else: print("Database operation failed, keeping my-modal open") return True, False except Exception as e: logging.error(f"Database error: {str(e)}") return True, False # 保持表单开启 return dash.no_update, dash.no_update success-modal还是闪退
最新发布
03-14
@app.callback( [Output("my-modal", "is_open"), Output("success-modal", "is_open")], [Input("submit-btn", "n_clicks"), Input("custom-close-icon", "n_clicks"), Input("close-modal", "n_clicks")], [State("my-modal", "is_open"), State("sn", "value"), State("ip", "value"), State("fp", "value"), State("type", "value"), State("pi-ip", "value")], prevent_initial_call=True ) def handle_modal_actions(submit_clicks, custom_close_clicks, close_clicks, is_open, sn, ip, fp, device_type, pi_ip): ctx = dash.callback_context if not ctx.triggered: return dash.no_update trigger_id = ctx.triggered[0]["prop_id"].split(".")[0] print(f"trigger_id={trigger_id}") if trigger_id == "custom-close-icon": return not is_open, dash.no_update if trigger_id == "submit-btn": if not all([sn, ip, fp, device_type]): logging.warning("Missing required fields") return dash.no_update try: # 动态构建SQL语句 columns = ["serialnumber", "dut_ip", "floorplan", "device_type", "team", "available"] values = [sn, ip, fp, device_type, "local", "1"] if pi_ip: columns.append("pi_ip") values.append(pi_ip) query = f""" INSERT INTO devices ({', '.join(columns)}) VALUES ({', '.join(['%s'] * len(values))}) """ # 执行数据库操作 success = db_execute(query, tuple(values)) if success: # 关闭原模态框并打开成功提示 return False, True else: # 保持原模态框打开(可添加错误提示) return True, False except Exception as e: logging.error(f"Database error: {str(e)}") return True, False # 保持表单开启 return dash.no_update, dash.no_update 提交之后弹窗闪退,没有通过点击消失
03-14
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