eval() The eval() method is used to return the value of the instructions within the parentheses. It will accept a string of statements and execute the string as source code, then return the result. syntax: eval(command) eval(string) EXAMPLE function evalIt() { eval(document.form1.input1.value); } This example is used to evaluate the JavaScript string which is entered in the textbox form control (form1, input1). The string od commands are executed, and the result is returned.