Evaluate

eval loads a page, evaluates one JavaScript expression, and writes JSON:

bash

jint-browser eval https://example.org/ "document.title"
jint-browser eval https://example.org/ \
  "[...document.querySelectorAll('article')].map(x => x.textContent)"

The expression is parenthesized and evaluated in the page. JSON.stringify also runs in the page, so Date, toJSON, NaN, and other JavaScript semantics apply. Values for which JSON.stringify returns undefined—such as top-level undefined, functions, and symbols—are written as null.

This command evaluates an expression, not an arbitrary statement list. A bare await is not enabled. Use an expression that returns the current value after the selected load state.

eval accepts the same loading and browser options as fetch:

bash

jint-browser eval https://example.org/app \
  "document.querySelectorAll('.row').length" \
  --wait-until networkidle \
  --timeout 30s \
  --header 'X-Test: true' \
  --cookie session=abc

If an expression begins with a dash, end option parsing first:

bash

jint-browser eval https://example.org/ -- "-1 + 2"

An expression that throws exits with code 4 and writes the error to standard error.

Evaluate ​

Evaluate