ssssssss-team/spider-flow · error · TypeError

" + g + " is not a function

Error message

" + g + " is not a function

What it means

The same Array.prototype.forEach polyfill in formSelects-v4.js validates its first argument. If the callback `g` is not a function it throws TypeError(g + ' is not a function'), mirroring the ES5 specification. The odd message text with escaped quotes is an artifact of how the error was captured/escaped.

Solutions

1. Ensure the first argument to forEach is a function; check the callback variable is defined and spelled correctly.
2. Guard: `if (typeof cb === 'function') arr.forEach(cb)`.
3. Fix argument order if values were swapped at the call site.

Example fix

// before
list.forEach(callbackName); // callbackName is undefined
// after
if (typeof callbackName === 'function') { list.forEach(callbackName); }

if (typeof callback !== 'function') { throw new TypeError('forEach callback must be a function, got: ' + callback); } items.forEach(callback);

function isFunction(v) { return typeof v === 'function'; }

try {
  items.forEach(callback);
} catch (e) {
  if (e instanceof TypeError && /is not a function/.test(e.message)) { callback = defaultCallback; items.forEach(callback); }
  else throw e;
}

When it happens

Trigger: Passing a non-function (undefined, null, string, object) as the first argument to forEach, typically because the callback variable is undefined due to a typo, failed lookup, or wrong argument order.

Common situations: Calling `arr.forEach(arr[i])` style mistakes, callbacks returned from optional APIs that came back undefined, refactors that renamed the callback function but not all call sites, in environments relying on the polyfill (old IE).

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• this is null or not defined
• This is abstract class

AI-assisted analysis of ssssssss-team/spider-flow@c799cca99c (2026-09-08). Data as JSON: /api/errors/3f3843d75b102d0f. Report an issue: GitHub.

Appendix: source

Thrown at spider-flow-web/src/main/resources/static/js/layui/extends/formSelects-v4.js:208

				    c,
				    e = Object(this),
				    f = e.length >>> 0;if (h) {
					b = h;
				}a = new Array(f);c = 0;while (c < f) {
					var d, g;if (c in e) {
						d = e[c];g = i.call(b, d, c, e);a[c] = g;
					}c++;
				}return a;
			};
		};

		//拓展Array foreach方法
		if (!Array.prototype.forEach) {
			Array.prototype.forEach = function forEach(g, b) {
				var d, c;if (this == null) {
					throw new TypeError("this is null or not defined");
				}var f = Object(this);var a = f.length >>> 0;if (typeof g !== "function") {
					throw new TypeError(g + " is not a function");
				}if (arguments.length > 1) {
					d = b;
				}c = 0;while (c < a) {
					var e;if (c in f) {
						e = f[c];g.call(d, e, c, f);
					}c++;
				}
			};
		};

		//拓展Array filter方法
		if (!Array.prototype.filter) {
			Array.prototype.filter = function (b) {
				if (this === void 0 || this === null) {
					throw new TypeError();
				}var f = Object(this);var a = f.length >>> 0;if (typeof b !== "function") {
					throw new TypeError();
				}var e = [];var d = arguments[1];for (var c = 0; c < a; c++) {

View on GitHub (pinned to c799cca99c)