JavaScript simple way to determine whether the input content is legitimate _javascript tips

This example describes how JavaScript is a simple way to determine whether the input is legitimate. Share to everyone for your reference, specific as follows:

The idea of detecting the illegal character detection in the content of user input

1, the definition of a valid string (source string)
2, get the user input content
3, loop out the user input every character, go to the source string to find
1), search found, return the location of the string lookup
2), did not find the return-1, we just use-1 to detect the user input is legitimate

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