Webview.eval() | LuaRT free and open source Windows programming framework for Lua

Webview:eval(expr) method

Execute JavaScript code in the current top level document rendered in the WebView.

Parameters

expr

A string representing a valid Javascript expression to be evaluated.

Return value

This function returns a Task instance. Once finished, the Task will return two values :

A boolean indicating if the operation succeeded
A string representing either an error message in case of failure, or the result as a JSON encoded string

Example


local ui = require "ui"
require "webview"

-- create a simple Webview 
local win = ui.Window("Webview:eval() sample", 640, 480)
local Webview = ui.Webview(win, { url = "https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/PI" }, 0, 50, 640, 500)

local button = ui.Button(win, "Evaluate Javascript Math.PI")
button:center()
button.y = 10

function button:onClick()
    Webview:eval("Math.PI").after = function(success, result)
        if success then
            ui.info(result, "Math.PI value from Javascript")
        else
            ui.error(result)
        end
    end
end
              
-- update user interface
ui.run(win):wait()