what is strict mode in java script 3f

1Strict mode changes previously accepted "bad syntax" into real errors.
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3As an example, in normal JavaScript, mistyping a variable name creates a 
4new global variable. In strict mode, this will throw an error, making it 
5impossible to accidentally create a global variable.
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7In normal JavaScript, a developer will not receive any error feedback assigning
8values to non-writable properties.
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10In strict mode, any assignment to a non-writable property, a getter-only 
11property, a non-existing property, a non-existing variable, or a non-existing 
12object, will throw an error.
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14Strict mode makes it easier to write "secure" JavaScript.