@allnulled/check-that

Simple JavaScript library to make checkings in a semantic-friendly syntax.

Examples

import Check from "@allnulled/check-that";

Check.that("").isString().and.hasLengthLowerThan(1);
Check.that(true).isBoolean();
Check.that(5).isNumber();
Check.that(5).equals(5);
Check.that(undefined).isUndefined();
Check.that(5).isNotUndefined();
Check.that("").isString();
Check.that({}).isObject();
Check.that(Check).isFunction();
Check.that([]).isArray();
Check.that(5).isGreaterThan(4);
Check.that(5).isLowerThan(6);
Check.that(new Date()).isInstanceOf(Date);
Check.that(new Date()).isDate();
Check.that([5]).hasLengthGreaterThan(0);
Check.that([5]).hasLengthLowerThan(2);
Check.that(5).can(v => v === 5); // The function must return true, otherwise an error will arise
Check.that(5).cannot(v => v !== 5); // The function must return false, otherwise an error will arise
Check.that(5).throwsOn(v => {throw new Error()});
Check.that(5).doesNotThrowOn(v => undefined);

How it works

• Check is the main class.
• Check.that(value) is the same as new Check(value), is a static constructor.
• The main class' constructor has the following signature:
  • Check.that(target:any, targetID:String = "?", errorID:String = "xxxxx")
• The main class has these methods with these signatures:
  • isBoolean()
  • isString()
  • isNumber()
  • equals(value:any, valueID:String = undefined)
  • isUndefined()
  • isNotUndefined()
  • isString()
  • isObject()
  • isFunction()
  • isArray()
  • isDate()
  • isIntanceOf(clazz:Function, clazzID:String = undefined)
  • isGreaterThan(value:any, valueID:String = undefined)
  • isLowerThan(value:any, valueID:String = undefined)
  • hasLengthGreaterThan(value:any, valueID:String = undefined)
  • hasLengthLowerThan(value:any, valueID:String = undefined)
  • can(filter:Function, filterID:String = undefined)
  • cannot(filter:Function, filterID:String = undefined)
  • throwsOn(filter:Function, filterID:String = undefined)
  • doesNotThrowOn(filter:Function, filterID:String = undefined)
• When one of these methods fails, an error is thrown.
• When one of these methods succeeds, the Check instance itself is returned, in order to chain other checks against the same target.
• The thrown errors have the format:
  • "Expected <{ targetID }> to { type of check expression provided by the method } { valueID when used } [ERROR:{ errorID }]"
• Sometimes, intermediate operations fail. You can find some expression like -comparable as- on the error message when this happens.
• Finally, you can chain checks using .and, or not using it too.

License

Do what you want with it, no license.