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title
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With
JavaScript's with statement is a shorthand way to edit several properties on one object. Most developers discourage its usage, with best practice being not to use with. See Alternatives below for other approaches.
Note: "strict mode" in ECMAScript 5 forbids usage of with.
Syntax
with (expression)
statement
Example Usage
In JavaScript, you can individually modify an object's properties as below:
let earth = {};
earth.moons = 1;
earth.continents = 7;
with gives you a shorthand way to modify the properties on an object:
with (earth) {
moons = 1;
continents = 7;
}
While this example is contrived, you can understand cases of with better if you use larger objects as below:
earth.continents.australia.geography.ocean = "Pacific";
earth.continents.australia.geography.river = "Murray";
earth.continents.australia.geography.mountain = "Kosciuszko";
Alternatives
You should not use with, as it has subtle bugs and compatibility issues. A highly recommended approach is to assign the object to a variable, and then to modify the variable's properties. Here is an example using a larger object:
let earth = {
continents: {
australia: {
geography: {}
}
}
};
let geo = earth.continents.australia.geography;
geo.ocean = "Pacific";
geo.river = "Murray";
geo.mountain = "Kosciuszko";
Try It Out
More Information:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/with
https://yuiblog.com/blog/2006/04/11/with-statement-considered-harmful/