ECMAScript 6 (ES2015) added the ‘let’ keyword. let works a lot like the legacy ‘var’ keyword, but adds scoping capabilities.
Unfortunately, support cannot be retrofitted to older browsers with a polyfill, supported by IE11(with limitations), Edge 12+, Firefox 44+, Chrome 49+, Safari 10+. If you still need to support older browsers or devices you may want to stick with var.
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