Angular StrictNullChecks: "Error - object may be null"

I am encountering an issue with the 'strictNullChecks' setting in my Angular project. This has resulted in numerous errors across my templates (.html), such as:


      <input
        #inputValue
        type="text"
        (keyup.enter)="showStyle(inputValue.value)"
      />

    <p id="addStyle" style="color: blue; display: none" #hide>HELLO</p>

This error is also present in my TypeScript (.ts) files:

      addingStyle = window.document.getElementById("addStyle") as HTMLParagraphElement;

      showStyle(inputValue: string) { 
        if (inputValue === "help") {
          this.addingStyle.style.display = "block";
          console.log("help");
        } else {
          console.log("it worked");
        }
      }

Specifically, the error being displayed is:

Object is possibly 'null'.

angulartypescriptobjectdomnull

Answer №1

According to the information outlined in the guidelines

To prevent such errors, utilize the non-null assertion operator ! at the conclusion of a nullable expression.

YourComponent.ts

 styledElement = window.document.getElementById("styleMe")! as HTMLDivElement;

YourComponent.html

 <input
        #inputValue
        type="text"
        (keyup.enter)="applyStyle(inputValue!.value)"
      />

Answer №2

It's unclear whether the error pertains to addingStyle or inputValue, but in the configuration file tsconfig.json, you have the option to disable strictNullChecks:

{
  "compilerOptions": {
    "module": "commonjs",
    "target": "es5",
    "noImplicitAny": true,
    "strictNullChecks": false, // This can be changed
    "outDir": "./dist"
  },
  "include": [
    "src/**/*"
  ]
}

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