Set the value of a dropdown list/popup list to null or blank

 
• Customer is using the code nlapiSetFieldValue('leadsource',null, false, true); to set the value of popup list to blank
• Customer noticed that if the list becomes a dropdown, the code does not seem to work and value cannot be set to blank
• Note that the display type depends on the setting of Maximum Entries in Dropdowns under Home > Set Preferences. If you always want your lists to pop up, set the maximum to zero. If you always want lists to be dropdowns, set the maximum to 500. Display type depends on each user's preference.

Using 'null' to set the list value to blank only works for popup list. This does not work when the list becomes a dropdown. The solution is to use the following code to set both the popup and dropdown lists to blank.

nlapiSetFieldValue('leadsource','', false, true);