ECMAScript Built-ins

Native JavaScript built-in objects and methods available in SSJS — which Array, String, Math, and Number methods work, which are broken, and which require polyfills.

SSJS runs on the JINT engine with ES3/ES5 compatibility. Most native ECMAScript built-ins work as expected, but some methods are missing or behave incorrectly. This section documents what is safe to use.

For missing methods, see Polyfills and Missing Methods.

Quick Reference

Array Methods

Method	Status	Notes
Array.prototype.concat(...)	✅ Works
Array.prototype.join(sep)	✅ Works
Array.prototype.length	✅ Works
Array.prototype.pop()	✅ Works
Array.prototype.push(item)	✅ Works
Array.prototype.reverse()	✅ Works
Array.prototype.shift()	✅ Works
Array.prototype.slice(start, end)	✅ Works
Array.prototype.sort(fn)	✅ Works
Array.prototype.unshift(item)	✅ Works
Array.prototype.splice(start, count)	⚠️ Broken — polyfill	Ignores parameters; see Polyfills
Array.prototype.lastIndexOf(item)	⚠️ Broken — polyfill	Always returns -1; see Polyfills
Array.prototype.copyWithin(...)	⚠️ Polyfill	See Polyfills
Array.prototype.entries()	⚠️ Polyfill	See Polyfills
Array.prototype.fill(value)	⚠️ Polyfill	See Polyfills
Array.prototype.findIndex(fn)	⚠️ Polyfill	See Polyfills
Array.prototype.includes(item)	⚠️ Polyfill	See Polyfills
Array.prototype.indexOf(item)	⚠️ Polyfill	See Polyfills
Array.prototype.reduceRight(fn)	⚠️ Polyfill	See Polyfills
Array.isArray(val)	⚠️ Polyfill	See Polyfills
Array.of(...)	⚠️ Polyfill	See Polyfills
Array.prototype.every(fn)	❌ Missing	Use for loop
Array.prototype.filter(fn)	❌ Missing	Use for loop or polyfill
Array.prototype.find(fn)	❌ Missing	Use for loop or polyfill
Array.prototype.forEach(fn)	❌ Missing	Use for loop or polyfill
Array.prototype.map(fn)	❌ Missing	Use for loop or polyfill
Array.prototype.reduce(fn)	❌ Missing	Use for loop or polyfill
Array.prototype.some(fn)	❌ Missing	Use for loop or polyfill

String Methods

Method	Status	Notes
String.prototype.charAt(i)	✅ Works
String.prototype.charCodeAt(i)	✅ Works
String.prototype.concat(...)	✅ Works
String.prototype.indexOf(sub)	✅ Works
String.prototype.lastIndexOf(sub)	✅ Works
String.prototype.length	✅ Works
String.prototype.match(regex)	✅ Works
String.prototype.replace(search, rep)	✅ Works	Regex supported
String.prototype.search(regex)	✅ Works
String.prototype.slice(start, end)	✅ Works
String.prototype.split(sep)	✅ Works
String.prototype.substr(start, len)	✅ Works	ES3 Annex B; prefer substring
String.prototype.substring(start, end)	✅ Works
String.prototype.toLowerCase()	✅ Works
String.prototype.toUpperCase()	✅ Works
String.fromCharCode(code)	✅ Works	Static method
String.prototype.trim()	⚠️ Polyfill	See Polyfills
String.prototype.endsWith(sub)	❌ Missing	ES6; use polyfill or lastIndexOf
String.prototype.includes(sub)	❌ Missing	ES6; use indexOf !== -1
String.prototype.padEnd(len, ch)	❌ Missing	ES6; implement manually
String.prototype.padStart(len, ch)	❌ Missing	ES6; implement manually
String.prototype.repeat(n)	❌ Missing	ES6; loop instead
String.prototype.startsWith(sub)	❌ Missing	ES6; use polyfill or indexOf

Math Object

Method / Constant	Status
Math.abs(x)	✅ Works
Math.acos(x)	✅ Works
Math.asin(x)	✅ Works
Math.atan(x)	✅ Works
Math.atan2(y, x)	✅ Works
Math.ceil(x)	✅ Works
Math.cos(x)	✅ Works
Math.E	✅ Works
Math.exp(x)	✅ Works
Math.floor(x)	✅ Works
Math.LN2	✅ Works
Math.LN10	✅ Works
Math.log(x)	✅ Works
Math.LOG10E	✅ Works
Math.LOG2E	✅ Works
Math.max(a, b, ...)	✅ Works
Math.min(a, b, ...)	✅ Works
Math.PI	✅ Works
Math.pow(base, exp)	✅ Works
Math.random()	✅ Works
Math.round(x)	✅ Works
Math.sin(x)	✅ Works
Math.sqrt(x)	✅ Works
Math.SQRT1_2	✅ Works
Math.SQRT2	✅ Works
Math.tan(x)	✅ Works

Number

Method / Constant	Status	Notes
Number.prototype.toFixed(digits)	✅ Works
Number.prototype.toExponential([digits])	✅ Works
Number.prototype.toPrecision([digits])	✅ Works
Number.prototype.toString([radix])	✅ Works
Number.prototype.valueOf()	✅ Works
Number.MAX_VALUE	✅ Works
Number.MIN_VALUE	✅ Works
Number.NaN	✅ Works
Number.NEGATIVE_INFINITY	✅ Works
Number.POSITIVE_INFINITY	✅ Works
Number.isFinite(val)	❌ Missing	ES6; use global isFinite()
Number.isInteger(val)	❌ Missing	ES6; use val === Math.floor(val)
Number.isNaN(val)	❌ Missing	ES6; use global isNaN()
Number.parseInt(str)	❌ Missing	ES6; use global parseInt()
Number.parseFloat(str)	❌ Missing	ES6; use global parseFloat()

Object Methods

Method	Status	Notes
Object.prototype.hasOwnProperty(v)	✅ Works	Use inside for...in to skip inherited properties
Object.keys(obj)	❌ Missing	ES6; use for...in with hasOwnProperty
Object.values(obj)	❌ Missing	ES6; use for...in with hasOwnProperty
Object.assign(target, ...src)	❌ Missing	ES6; copy properties manually

In This Section

Page	Description
Array Methods	Safe and polyfillable array methods
String Methods	Safe and polyfillable string methods
Math	Math object reference
Number Methods	Number methods, constants, and global numeric functions
Object Methods	hasOwnProperty and missing Object statics