Memoize does exactly what the name says! It takes a function, and returns a version of it that will only calculate its return value once for a given set of inputs, and then cache this value and return it on subsequent calls.

but this won't work, since person2 is out of scope! this will print out 'bill' again, since the for uses the parent's scope Underscore’s each function is a great alternate to Javascript’s built in for function, with the key difference that it allows you to have a local scope to work in (as opposed to Javascript’s built in for, which inherits the parent scope). I’ve compiled a few of my favorites here: _.each What you may not know is that _.js is bundled with Alloy, letting you use the awesome collection of commonly used functions with little effort on your part. O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top (_.js for short) is a phenomenal javascript library that most web and Titanium developers are likely familiar with at this point. Get Mastering JavaScript Single Page Application Development now with the O’Reilly learning platform. The _.template() method can also be used to parse and execute arbitrary JavaScript code within a template. The variable name would be dynamically passed in to the compiled function for this template. Īn Underscore.js template expression used within HTML looks like the preceding example.

Underscore.js template syntax delimiters resemble those of the ERB, or Embedded Ruby template syntax, with an equals sign following the opening tag: Hello.

This method is used to compile strings with expressions into functions that replace those expressions with dynamic values. One of those utility methods is _.template(). The Underscore.js library is well known for its useful JavaScript functional programming helpers and utility methods.

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