The use strict literal is entered at the top of a JavaScript program or at the top of a function. It helps you write safer JavaScript code by throwing an error if a global variable is created by mistake. For example, the following program will throw an error:
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function doSomething(val) { "use strict"; x = val + 10;}console.log(doSomething(10));// It will throw an error because `x` was not defined and it is being set to// some value in the global scope, which isn't allowed with `use strict`.// The small change below fixes the error being thrown:function doSomething(val) { "use strict"; var x = val + 10; return x;}console.log(doSomething(10));OUTPUT
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