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Is there any way to access the javascript template-string engine to provide default values for undefined variables?
console.log(`this variable is undefined: ${x}`)
// throws ReferenceError
// but i want to generate something like this:
"this variable is undefined: <warning! undefined variable>"
This would be ok, too:
function tag(strings,...values){
// values[i] should be "undefined" if this variable is undefined
}
tag`${x}`
If thats not possible, is there a template string engine that does exactly what javascript does and has this feature?
787
Template strings are a powerful feature of modern JavaScript released in ES6. It lets us insert/interpolate variables and expressions into strings without needing to concatenate like in older versions of JavaScript. It allows us to create strings that are complex and contain dynamic elements.
Template literals are a new feature introduced in ECMAScript 2015/ ES6. It provides an easy way to create multiline strings and perform string interpolation. Template literals are the string literals and allow embedded expressions. Before ES6, template literals were called as template strings.
In JavaScript, function parameters default to undefined . However, it's often useful to set a different default value.
In JavaScript, the template string implements the string interpolation. A template string is defined by wrapping a sequence of characters into a pair of backticks `I'm template string` . The template string placeholders have the format ${expression} , for example `The number is ${number}` .
You can use the || to coalasce the value, like:
console.log(`this variable is undefined: ${x || '<warning! undefined variable>'}`)
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