April, 2016
using underscore to verify if a variable is undefined or null
Example of if a variable is undefined
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function test() { console.log(_.isUndefined(foo)); // true, no error due to hoisting var foo = 3; console.log(_.isUndefined(foo)); // false, foo is defined now. } |
Example of if a variable is null function test() { var foo = null; console.log(_.isNull(foo)); // true, var foo = 3; console.log(_.isNull(foo)); // false, }