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extras/js-lazy.md

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+---
+title: JavaScript lazy shortcuts
+category: JavaScript
+---
+
+| What | Lazy mode | "The right way" |
+| --- | --- | --- |
+| String to number | `+str` | `parseInt(str, 10)` or `parseFloat()` |
+| Math floor | `num | 0` | `Math.floor(num)` |
+| Number to string | `'' + num` | `num.toString()` |
+| Date to UNIX timestamp | `+new Date()` | `new Date().getTime()` |
+| Any to boolean | `!!value` | `Boolean(value)` |
+| Check array contents | `if (~arr.indexOf(v))` | `if (arr.contains(v))` \* |
+
+> * = `.contains` is ES6-only, otherwise use `.indexOf(val) !== -1`
+
+## Examples
+
+```js
+n = +'4096'    // n === 4096
+s = '' + 200   // s === '200'
+```