How can I extract with cpqjs the standard field "discount_percent_l" from the line item grid?

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Hello,

We would like to extract with cpqjs the standard field "discount_percent_l" from the line item grid. How can I do it?

We tried to execute the following code:

x = CPQJS.getAttributeVal('discountPercent_l');

but it goes in error

Regards,

Silvia

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