jQuery globalEval() Method

What Is globalEval()?

jQuery.globalEval(code) (alias $.globalEval) executes a JavaScript string in the global scope (since jQuery 1.0.4). Unlike eval(), declarations become true globals — important when loading scripts dynamically.

$.globalEval(code)                    // jQuery 1.0.4+
$.globalEval(code, { nonce: "..." })  // jQuery 3.4+ (CSP)
$.globalEval(code, options, doc)      // jQuery 3.5+ (iframe doc)

function test() {
  $.globalEval("var newVar = true;");
}
test();
// newVar === true  (global!)

How to Use globalEval()

Pass a trusted code string; optionally add CSP nonce or a target document.

1. Start with a trusted JavaScript string (never user input).
2. Call $.globalEval(code) so var / function declarations land on the global object.
3. On CSP sites (jQuery 3.4+), pass { nonce: "..." } as the second argument.
4. For iframes (jQuery 3.5+), pass the iframe’s contentDocument as the third argument.

Pseudocode

function globalEval(code, options, doc):
    targetDoc = doc or current document
    // run code in targetDoc's global scope
    // (not the calling function's local scope)
    return result of last expression

// Official pattern:
function test():
    $.globalEval("var newVar = true;")
test()
// newVar is now a global → true

Cheat Sheet

Keep these facts handy while working with global script strings.

Live Preview

Pick a trusted sample string and run it with $.globalEval.

sample = Create global flag
code = "var geLiveFlag = true;"
geLiveFlag → true

jQuery Examples

Short, copy-ready snippets. Open DevTools Console, or use Try It Yourself for a live editor.

function test() {
  jQuery.globalEval("var newVar = true;");
}
test();

console.log(typeof newVar);  // "boolean"
console.log(newVar);         // true

boolean
true

function demo() {
  $.globalEval("var fromGlobalEval = 'global';");
  eval("var fromEval = 'local';");
}
demo();

console.log(typeof fromGlobalEval);  // "string"
console.log(typeof fromEval);        // "undefined"

string
undefined

var script = [
  "window.demoCounter = 0;",
  "window.incrementDemo = function () {",
  "  window.demoCounter++;",
  "  return window.demoCounter;",
  "};"
].join("\n");

$.globalEval(script);

console.log(incrementDemo());  // 1
console.log(incrementDemo());  // 2

1
2

function test() {
  jQuery.globalEval("var cspVar = true;", {
    nonce: "nonce-2726c7f26c"
  });
}
test();

console.log(cspVar);  // true

true

Performance Notes

Parsing a string every time is slower than calling a normal function. Evaluate once, then call the globals you defined — do not re-run large strings on every click or animation frame.

Key Takeaways