# Which component triggered the callback

**URL:** <https://community.plotly.com/t/which-component-triggered-the-callback/7366>\
**Category:** Dash Python\
**Created:** [December 17, 2017, 9:59am UTC](https://community.plotly.com/t/which-component-triggered-the-callback/7366 "2017-12-17T09:59:32Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![troystory89](https://avatars.discourse-cdn.com/v4/letter/t/a6a055/32.png) [@troystory89](https://community.plotly.com/u/troystory89)\
**Post date:** [January 8, 2019, 9:09pm UTC](https://community.plotly.com/t/which-component-triggered-the-callback/7366/4 "2019-01-08T21:09:29Z")

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Thanks Mccalluc, Great idea.  
I implemented your method and I thought id show a simplified example of it.

Please note all the potential problems Mccalluc pointed out.

You can add as many html/dcc components as you want, following the same pattern with the timekeeper divs.

```
import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output
import time

app = dash.Dash()

app.layout = html.Div([

    # hidden div for holding timestamp of any DCC or html component
    html.Div(id='dcc-timekeeper', children='0', style={'display': 'none'}),

    # Any DCC or html item you want to use for ordered trigger
    dcc.Dropdown(id='dcc-item',
                 options=[
                     {'label': 'Chriddyp', 'value': 'Hr'},
                     {'label': 'Please notice me', 'value': 'Day'}
                 ],
                 value='Hr'
                 ),

    # 3 buttons to compare to for ease (these can use n_clicks_timestamp like in previous examples)
    html.Button(id='btn1',
                children='btn1',
                n_clicks_timestamp='0'),

    html.Button(id='btn2',
                children='btn2',
                n_clicks_timestamp='0'),

    html.Button(id='btn3',
                children='btn3',
                n_clicks_timestamp='0'),

    html.Div(id='results')

])

# use your DCC or html item to trigger a callback to update the dcc-timekeeper div
@app.callback(Output('dcc-timekeeper', 'children'),
              [Input('dcc-item', 'value')])
def update_timebase_nclick(value):
    return '{}'.format(int(time.time() * 1000))

# use multiple inputs and figure out which one was the trigger as such:
@app.callback(Output('results', 'children'),
              [Input('btn1', 'n_clicks_timestamp'),
               Input('btn2', 'n_clicks_timestamp'),
               Input('btn3', 'n_clicks_timestamp'),
               Input('dcc-timekeeper', 'children'),
               Input('dcc-item', 'value')])
def slider_buttons(btn1, btn2, btn3, btn4, dccvalue):
    if int(btn1) > int(btn2) and int(btn1) > int(btn3) and int(btn1) > int(btn4):
        val = 'btn1'
    elif int(btn2) > int(btn1) and int(btn2) > int(btn3) and int(btn2) > int(btn4):
        val = 'btn2'
    elif int(btn3) > int(btn1) and int(btn3) > int(btn2) and int(btn3) > int(btn4):
        val = 'btn3'
    elif int(btn4) > int(btn1) and int(btn4) > int(btn2) and int(btn4) > int(btn3):
        val = 'Dcc item'
    return '{}'.format(val)

if __name__ == ' __main__':
    app.run_server(debug=True)
```

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