Assertions & checkers for variables value

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Include

package.json:

"dependencies": {
  "@jzucen/asserts-js": "git+https://gitflic.ru/project/jzucen/asserts-js.git"
}

Import

import { asserts, checks } from '@jzucen/asserts-js';

const someVar = 'test value';
asserts.inspect('inspected variable name', someVar).isString().isEmpty(); // throws AssertError in isEmpty()
console.log(checks.inspect('someVar', 'variable value').not().isInteger()); // output: "true"

Properties & methods of asserts

• ^✱ – always return a new instance;
• ^✱✱ – return either a new instance or the original if property inverted remains unchanged;
• ^✱✱✱ – only applies to the next statement, then returns to the original instance;
• methods that perform assertion checking either throw an exception or return the (original) instance.

Properties & methods of checks

• Is a proxy for the assertion object, meaning it has the same properties and methods.
• Assertion checking methods return true or false instead of the original object.
• Has an additional property lastError containing error information if the last check returned false.

Register custom asserts

import { asserts, checks } from '@jzucen/asserts-js';

asserts.register(
  'newAssertName', // assert name (valid function name)
  (asserts, message, ...params) => { // positive (!!!) assert
    // asserts – link to this (asserts/cheks)
    // message – registered error message
    // params – additional parameters to check
    const [top] = params;
    asserts.isInRange(0, top).not().isEqualTo(top);
    // may not return anything - this is not necessary
  },
  'Assertion of {#name} was fail'
);

console.log(
  checks.inspect('myVar', 100).newAssertName(100), // output: "false"
  checks.lastError // output: AssertError: Value of "myVar" must not be equal to "100" but "100" is given
);